I'm not sure your question makes sense, you mean stand alone FCGI instance .vs running FCGI on multiple servers?
If you will check FastCGI's documentation, you will find that there are three ways to implement FastCGI:
I understand what external means but didn't get how static fastcgi and dynamic fastcgi differ especially in virtual hosts environment.
Also, does not hurt to take a look into Lighttpd instead of Apache 2.
Lighttpd does not support mod_rewrite syntax. Nor does it support .htaccess type file where I can change my rewrite rules by simply editing .htaccess file. At least, that was how it was last time I had a look.