Magento, replace block on product view on custom theme - magento

Question

We have a custom theme from a 3rd provider. The provider left some blank spaces where it is possible to add some more information. I already have settled up a custom layout, it reads the nedeed block and paints whatever I need but only on the content or head reference blocks. I can not find the needed block to be referenced to add there the needed information. I guess it should be inside the catalog_product_view group. How can I find it? I've found some useful information here and here on StackOverflow, but can not get to the correct answer.
Here is what I have for now:
My layout file, banners.xml :
<?xml version="1.0" encoding="UTF-8"?>
<layout version="0.1.0">
<catalog_product_view>
<reference name="content">
<block type="banners/front" name="banners.front" as="banners_front"
template="banners/product.phtml" before="-"/>
</reference>
</catalog_product_view>
</layout>
My product.phtml file:
<div>
<h3>Hello...</h3>
<p>This is my custom block</p>
</div>
Here is the catalog_product_view group found on the layout file catalog.xml from the 3rd part theme:
<catalog_product_view translate="label">
<label>Catalog Product View (Any)</label>
<!-- Mage_Catalog -->
<reference name="root">
<action method="setTemplate"><template>page/1column.phtml</template></action>
</reference>
<reference name="head">
<action method="addJs"><script>varien/product.js</script></action>
<action method="addJs"><script>varien/configurable.js</script></action>
<action method="addItem"><type>js_css</type><name>calendar/calendar-win2k-1.css</name><params/><!--<if/><condition>can_load_calendar_js</condition>--></action>
<action method="addCss"><stylesheet>css/jquery.lightbox-0.5.css</stylesheet></action>
<action method="addCss"><stylesheet>css/slider.css</stylesheet></action>
<action method="addItem"><type>js</type><name>calendar/calendar.js</name><!--<params/><if/><condition>can_load_calendar_js</condition>--></action>
<action method="addItem"><type>js</type><name>calendar/calendar-setup.js</name><!--<params/><if/><condition>can_load_calendar_js</condition>--></action>
<action method="addItem"><type>js</type><name>lightbox/jquery.lightbox-0.5.min.js</name></action>
<action method="addJs"><script>slideshow/jquery.slider.js</script></action>
</reference>
<reference name="content">
<block type="catalog/product_view" name="product.info" template="catalog/product/view.phtml">
<!--
<action method="addReviewSummaryTemplate"><type>default</type><template>review/helper/summary.phtml</template></action>
<action method="addReviewSummaryTemplate"><type>short</type><template>review/helper/summary_short.phtml</template></action>
<action method="addReviewSummaryTemplate"><type>...</type><template>...</template></action>
-->
<block type="catalog/product_view_media" name="product.info.media" as="media" template="catalog/product/view/media.phtml"/>
<block type="core/text_list" name="alert.urls" as="alert_urls" translate="label">
<label>Alert Urls</label>
</block>
<action method="setTierPriceTemplate"><template>catalog/product/view/tierprices.phtml</template></action>
<block type="catalog/product_view_tabs" name="product.info.tabs" as="info_tabs" template="catalog/product/view/tabs.phtml" >
<action method="addTab" translate="title" module="catalog"><alias>description</alias><title>Product Description</title><block>catalog/product_view_description</block><template>catalog/product/view/description.phtml</template></action>
<action method="addTab" translate="title" module="catalog"><alias>additional</alias><title>Additional Information</title><block>catalog/product_view_attributes</block><template>catalog/product/view/attributes.phtml</template></action>
<action method="addTab" translate="title" module="review"><alias>product_review</alias><title>Reviews</title><block>review/product_view_list</block><template>review/product/view/list.phtml</template></action>
<block type="cms/block" name="product_custom_tab">
<action method="setBlockId"><block_id>product_custom_tab</block_id></action>
</block>
</block>
<block type="catalog/product_view_additional" name="product.info.additional" as="product_additional_data" />
<block type="catalog/product_view" name="product.info.addto" as="addto" template="catalog/product/view/addto.phtml"/>
<block type="catalog/product_view" name="product.info.addtocart" as="addtocart" template="catalog/product/view/addtocart.phtml"/>
<block type="core/text_list" name="product.info.extrahint" as="extrahint" translate="label">
<label>Product View Extra Hint</label>
</block>
<block type="catalog/product_list_related" name="related_products" as="related_products" translate="label" template="catalog/product/list/related.phtml">
<label>Related Products</label>
</block>
<block type="catalog/product_view" name="product.info.options.wrapper" as="product_options_wrapper" template="catalog/product/view/options/wrapper.phtml" translate="label">
<label>Info Column Options Wrapper</label>
<block type="core/template" name="options_js" template="catalog/product/view/options/js.phtml"/>
<block type="catalog/product_view_options" name="product.info.options" as="product_options" template="catalog/product/view/options.phtml">
<action method="addOptionRenderer"><type>text</type><block>catalog/product_view_options_type_text</block><template>catalog/product/view/options/type/text.phtml</template></action>
<action method="addOptionRenderer"><type>file</type><block>catalog/product_view_options_type_file</block><template>catalog/product/view/options/type/file.phtml</template></action>
<action method="addOptionRenderer"><type>select</type><block>catalog/product_view_options_type_select</block><template>catalog/product/view/options/type/select.phtml</template></action>
<action method="addOptionRenderer"><type>date</type><block>catalog/product_view_options_type_date</block><template>catalog/product/view/options/type/date.phtml</template></action>
</block>
<block type="core/html_calendar" name="html_calendar" as="html_calendar" template="page/js/calendar.phtml"/>
</block>
<block type="catalog/product_view" name="product.info.options.wrapper.bottom" as="product_options_wrapper_bottom" template="catalog/product/view/options/wrapper/bottom.phtml" translate="label">
<label>Bottom Block Options Wrapper</label>
<action method="insert"><block>product.tierprices</block></action>
<block type="catalog/product_view" name="product.clone_prices" as="prices" template="catalog/product/view/price_clone.phtml"/>
<action method="append"><block>product.info.addtocart</block></action>
<action method="append"><block>product.info.addto</block></action>
</block>
<block type="catalog/product_view" name="product.info.options.wrapper.bottom2" as="product_options_wrapper_bottom2" template="catalog/product/view/options/wrapper/bottom.phtml" translate="label">
<label>Bottom Block Options Wrapper</label>
<action method="insert"><block>product.tierprices</block></action>
<action method="append"><block>product.info.addtocart</block></action>
<action method="append"><block>product.info.addto</block></action>
</block>
<block type="core/template_facade" name="product.info.container1" as="container1">
<action method="setDataByKey"><key>alias_in_layout</key><value>container1</value></action>
<action method="setDataByKeyFromRegistry"><key>options_container</key><key_in_registry>product</key_in_registry></action>
<action method="append"><block>product.info.options.wrapper</block></action>
<action method="append"><block>product.info.options.wrapper.bottom2</block></action>
</block>
<block type="core/template_facade" name="product.info.container2" as="container2">
<action method="setDataByKey"><key>alias_in_layout</key><value>container2</value></action>
<action method="setDataByKeyFromRegistry"><key>options_container</key><key_in_registry>product</key_in_registry></action>
<action method="append"><block>product.info.options.wrapper</block></action>
<action method="append"><block>product.info.options.wrapper.bottom</block></action>
</block>
<block type="catalog/product_list_upsell" name="upsell_products" template="catalog/product/list/upsell.phtml">
<action method="setColumnCount"><columns>5</columns></action>
<action method="setItemLimit"><type>upsell</type><limit>5</limit></action>
</block>
<action method="unsetCallChild"><child>container1</child><call>ifEquals</call><if>0</if><key>alias_in_layout</key><key>options_container</key></action>
<action method="unsetCallChild"><child>container2</child><call>ifEquals</call><if>0</if><key>alias_in_layout</key><key>options_container</key></action>
</block>
</reference>
<reference name="product_review">
<block type="review/form" name="product.review.form" as="review_form">
<block type="page/html_wrapper" name="product.review.form.fields.before" as="form_fields_before" translate="label">
<label>Review Form Fields Before</label>
<action method="setMayBeInvisible"><value>1</value></action>
</block>
</block>
</reference>
<reference name="left">
<block type="catalog/product_list_related" name="catalog.product.related" before="-" template="catalog/product/list/related.phtml"/>
</reference>
</catalog_product_view>