Depending on the model of your Mac Pro, any modern monitor with the correct cable should work. In you are on the latest (2013, model 6,1), then any monitor up to 4K with a miniDP or HDMI connection will work.
I'm personally using a Dell 27" monitor connected via miniDP, works great.
You won't be able to change the brightness any non-Apple display with the brightness control keys on Mac keyboards (at least not without a script and custom software).
Depending on the model of your Mac Pro, any modern monitor with the correct cable should work. In you are on the latest (2013, model 6,1), then any monitor up to 4K with a miniDP or HDMI connection will work.
I'm personally using a Dell 27" monitor connected via miniDP, works great.
You won't be able to change the brightness any non-Apple display with the brightness control keys on Mac keyboards (at least not without a script and custom software).
I think the Windows key gets mapped to the Command key.
You can hook up any standard mouse. Fancy mice with lots of buttons would require a driver. There are many non-Apple branded mice that provide Mac drivers.
New logitech mice and keyboard have mac driver? Plug and play or I need to install? Thx.