Re: Issue with high-rate servers.

It's more of a guess, but I suppose that it might be related to the fact that servers seem to struggle with tickrate of 60Hz (or higher) so far, especially with high player count. Next time you play, check if any of these icons are present - people playing on trouble-riddled servers almost always see the first two icons, with high latency and/or latency variation often accompanying them (it happens regardless of their connection and for now seems to be a server-side problem):

Honestly? I'm afraid that nothing can really be done about these if the problems really are on server side.

About lower graphics settings messing your aim up... it'll only happen if you start downscaling resolution - it actually does make reaction time and accuracy worse (as spotting enemies is way tougher, and that might throw your aim off in some cases).