From what I've heard about the MX700, I wouldnt recommend getting one. I guess there's been a lot of returns of defective MX700s because their side buttons keep falling off.
Instead, I would recommend this mouse
It doesnt have the side buttons, but it is nice because it has a tilt wheel, its very responsive, its wireless, and its comfortable to use. I never thought I would be so pleased with a mouse...
I use this mouse on my desk with no pad.
It will work with firefox.
I tried just now to see if the mouse would work with the receiver up on a shelf, and it worked perfectly good.
As for the keyboard....If you can type above 100wpm, you might notice a lag between the keys you type and what appears on the screen.
Hope that helps