ElasticSearch NEST recreate index with zero downtime - elasticsearch

Question

I am writing backend in C# for a website. I'd like to recreate index with little downtime.
After reading these two posts:
Nest Client c# 7.0 for elastic search removing Aliases
Recreate ElasticSearch Index with Nest 7.x
I come up with this:
var alias_exist = await _client.Indices.ExistsAsync(index_string_alias);
if (alias_exist.Exists)
{
var oldIndices = await _client.GetIndicesPointingToAliasAsync(index_string_alias);
var oldIndexName = oldIndices.First().ToString();
await _client.Indices.BulkAliasAsync(new BulkAliasRequest
{
Actions = new List<IAliasAction>
{
new AliasRemoveAction {Remove = new AliasRemoveOperation {Index = oldIndexName, Alias = index_string_alias}},
new AliasAddAction {Add = new AliasAddOperation {Index = index_string_unique, Alias = index_string_alias}}
}
});
} else
{
var putAliasResponse = await _client.Indices.PutAliasAsync(new PutAliasRequest(index_string_unique, index_string_alias));
}
}
I'd like to remove index_string_alias if exists and assign the alias to the newly created index_string_unique.
Also, I'd like to confirm that I can treat the alias as the index name in my other queries.
I am really new to Elastic Search and wonder how people figure out these things. I searched through the official documentation and found little information about the async functions in NEST. Where should I look for explanations for functions?