Yes, Im pretty sure that web history is backed up. In fact, all settings and data is generally backed up. So, basically, if you bought a new iPod touch and restored it from the backup, it will be as if you are still using the original iPod.
IIRC you can't control what's backed up.
Okay so my next question is if I clear my history, cookies, cache and whatever else then sync and backup through iTunes will that erase the last backup an use this new one?