Is it possible to have the logged-in-user page view cached too?

What is the ratio of logged-in-user/total page request (among viewing of normal, cacheble page)

For a fixed skin and language what are the things that change on a logged-in user?

*the name of the user and the link to his/her user page (and similar) *the move link (but this is always the same) *the watch/unwatch link

Is there something more?

One more question: which is the part (Apache, Squid, Database, etc) which is at the moment the limiting factor in the MediaWiki cluster?

AnyFile