If your talking about category avatars this is not an issue and there is a workaround.
To set a category avatar the image needs to exist in the category you are trying to mark it the avatar of so you can move it to the cat mark make index thumb and then move it back.
The comments do not appear as they use to in earlier versions as alot of the comments stuff is ajax now.
As far time being off thats easy. Most applications including ours allows users to set a time offset and its based on server time. Now vbulletin uses absolutely GMT time as they think everyone is from London.
Invisionboard does the same thing but those are the only two applications I know that do this. Now we have a setting to sync times it is called the GMT time offset in Global Options in Admin. For instance my server is EST which is -5 hours from GMT in London so in that spot I put a 5 and save. My times now work and display the same as vbulletin.