Ok, I took Rawhides advice to heart and changed it again. Full refresh should do it.
It's a low-priority program, so I think it only eats up the CPU you're not using for anything else. As for the laptop, there is an option to only allow folding if you're plugged in to a power source, so yes, it's possible. However, if you download the text-only console client (see Zargon's post a few pages back) there's shouldn't be any problems while playing games (the folding would just go slowing if you're gaming).
And yes, I believe you need internet connection.