Is there any gain using Memcached module when APC is running good on large Drupal 7 site (one server)
Putting the cache_form on the database is a good idea. I will help to prevent errors like this: http://drupal.org/node/500646

APC vs Memcache when it comes to the drupal cache mainly comes down to a persons preference. Mine is towards memcache because it allows for a multiple web head server setup. Performance wise APC will usually be a touch quicker, but my vote is still for memcache even on single server setups.