Full-Path Redirection and Domain Mapping

Okay, so I have a subdomain multisite WordPress network on Bluehost. The main blog has two domain names (domain1 and domain2). I’m trying to figure out how to redirect a full path associated with domain2 to the same path at domain1. In other words, if a user entered “http://thisdomain2.com/2011/pouting-cats/” they should arrive instead at “http://thisdomain1.com/2011/pouting-cats/”.

Second thing I’m trying to figure out how to do: I am designing a site within the network for a client, but the client’s site will have it’s own domain name (domain3) and must never appear associated with my main domain name(s)–domain1 and domain2. Preferably, even the WordPress login for this site will rest under domain3. I will add other similar sites eventually.

Here is my current HTACCESS:

RewriteEngine on
RewriteCond %{HTTP_HOST} ^domain2\.com$ [OR]
RewriteCond %{HTTP_HOST} ^www\.domain2\.com$ [OR]
RewriteCond %{HTTP_HOST} ^http\:\/\/www\.domain1\.com\/$
RewriteRule ^/?$ “http\:\/\/domain1\.com\/” [R=301,L]

# BEGIN WordPress
RewriteBase /
RewriteRule ^index\.php$ – [L]

# uploaded files
RewriteRule ^files/(.+) wp-includes/ms-files.php?file=$1 [L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ – [L]
RewriteRule . index.php [L]
# END WordPress