cant really comment on the headset, but for the mouse, i find that a trackball works only if you are doing like some basic net surfing and such, pretty much the stuff that you said you did.
but as far as for anything that requires a kind of faster response, it might be iffy. i have used one often at a relatives house, and even if im playing like a simple flash game or mmo, you need more of a two-button mouse to keep up with the game. this is just my view ofcourse, but i found it even more difficult to use when i tried playing a fps. some people might like it though. i found that since i wasent use to it, my thumb ended up hurting more because its what you really use to move the mouse.
if your wrist hurts a bit after a while, maybe you need something like this
Newegg.com - BELKIN WaveRest F8E244-BLK Gel Wrist Pad - Mouse Pads & Accessories
maybe not this exact one, but something like it. they have ones similar to this in my local library and they are actually pretty comfortable.