Rewriting domain only if not on local dev enviroment and forcing www with Mod Rewrite
Yes! That is indeed correct. From the docs for RewriteCond:


  'ornext|OR' (or next condition)
  
  Use this to combine rule conditions with a local OR instead of the
  implicit AND.


The [AND] flag is the default behaviour of combining multiple conditions expressions together.

As for the rule itself, I'd suggest using %{REQUEST_URI} instead of $1 in rewrites:

RewriteCond %{HTTP_HOST} !\.local$
RewriteCond %{HTTP_HOST} !^www\.
RewriteRule ^ http://www.%{HTTP_HOST}%{REQUEST_URI} [R=301,L]