I'm using a Logitech G9x. It's pretty handy dandy, can save 5 different DPI settings and switch on the fly. It's a nice fitting mouse, not big and bulky and taking up all your palm, so it's good for fingertip movement. Max DPI is... 5700, which happens to be what I usually set it at for games.
It's laser and corded, so no wireless crap to deal with and laser goodness too. Comes with weights so you can modify the weightyness (cool word i know).
Logitech make good mouse for man.
Torso twist limitations of mechs will be standard among all people I believe, however, you wont have to move your hand so much with a higher DPI.
I have a
Steel mousepad. Mine is about 2' x 2.5' Never have to worry about falling off (which isn't an issue at all with my high DPI). I like the feel of a single level surface under my arm/wrist, rather than having the bump of a pad somewhere.
Only button config i do is
LMB = fire 1
RMB = fire 2
and my 2 side buttons are for FRAPS vid record and screenie
as for the joystick thing: Quite possible to use a stick for those features. I myself am considering using my Cougar HOTAS throttle for my left hand and just using the buttons on it (since configuring the actual throttle part would be annoying as hell). If your stick allows you to bind its buttons to keystrokes, then you can do it with any stick. That just depends on your sticks software. Of course, if you can get your stick to naturally work with MWLL, you can just do that from ingame settings. But i have no idea what sticks are "supported" by MWLL right now.
good call on aiming with mouse.
