I've got a .htaccess file with numerous RewriteRules.

How do i exclude already established files and sites from getting tell you each one of the RewriteCond / RewriteRule pairs?

This:

RewriteCond %{REQUEST_FILENAME} -f 
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule .*  - [F,L]  

will not work dependably because based on this SO question:

inside the .htaccess context, [L] won't pressure mod_rewrite to prevent. it'll still trigger internal sub-demands:

How do i get this to work? Alternatively, is ther a control structure like if condition is applicable, undergo this block of rules, otherwise skip and visit finish in mod_rewrite?

The issue together with your rule is the fact that both conditions cannot be satisfied simultaneously just because a regular file (-f) cannot be also a directory (-d). Do this rather:

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule .* - [L]