.htaccess syntax code needing revision - xcode

Question

1) i am trying to 301 all non www's to www's (including files)
e.g. /subdirectory/ + /subdirectory/1.jpg (all possibilities with the www.)
2) i am trying to exclude ONLY but ALL .html and .php files from showing and would like only the non trailing version to be indexed, the rest to be 301's to my domain
e.g. /example.html or .php >> /example
e.g. /example.html or .php >> to not work + to not be indexed
e.g. /example to ONLY work and to ONLY be indexed (to avoid duplicate content)
3) i am trying to 301 all dead links and 404's to my domain
e.g. /deadlink or /deadlink.pdf >> 301'd to my domain, example.com
Here is the code i currently have, however i am not sure if it's 100% proper.
Can someone please reply with a validated syntax for these 3 tasks? Thanks.
Options +FollowSymLinks
RewriteEngine On
RewriteCond %{HTTP_HOST} ^example\.com$ [NC]
RewriteRule ^(.*)$ http://www.example.com/$1 [R=301,L]
RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}\.php -f
RewriteRule ^(.*)$ $1.php
RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}\.html -f
RewriteRule ^(.*)$ $1.html
RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule . / [L,R=301]

Answer 1

OK, you've got three parts you're trying for here, and I'll address them all separately.
Before we begin, you only need to have one
RewriteEngine on
It only needs to be turned on once.
You should also set:
Options -MultiViews
as MultiViews can otherwise cause some weird issues here.
Redirect to WWW
Your current rules should work, but you can simplify them a little using the != prefix on RewriteCond:
RewriteCond %{HTTP_HOST} !=www.example.com
RewriteRule ^(.*)$ http://www.example.com/$1 [R=301,L]
Removing .php and .html suffixes
You need two separate sets of rules here: one to remove suffixes from URLs, and another to readd them internally.
Let's do the second half first, since that's easier:
RewriteCond %{SCRIPT_FILENAME}.html -f
RewriteRule ^(.*)$ $1.html [L]
RewriteCond %{SCRIPT_FILENAME}.php -f
RewriteRule ^(.*)$ $1.php [L]
With this in place, though, removing suffixes is a little tricky without conflicting with the rule that goes ahead and tries to put them back on. The best approach I was able to come up with was:
RewriteCond %{THE_REQUEST} \.(html|php)
RewriteRule ^(.*)\.(html|php)$ $1 [R=301,L,NC]
But I'm open to suggestions.
301ing all dead links
Don't do that. If a link doesn't exist, it should return a page with a 404 status. If you want to redirect visitors to your home page from dead links, put a link in your 404 page.