I have a friend who has a Razer mouse and I didn't like the way the drivers were done, which is cloud based. I guess it will as well depend on what you want to do but any of the Logitechs such as the G500 or higher are great mice.
Razer makes decent mice but as I said, I don't like the driver setup.
if you look at my photo in my signature that pad is 11x17
standard mousepads are about 8x9.5
for gaming and such tasks a standard mousepad is a bit small but definitely works. an 11x17 is a bit large but also works well. i confess to only using a little over half of the actual mousepad but what i find nice is that i can adjust my arm position without readjusting the mousepad.
some of the very large sized pads are meant to put both the mouse and keyboard on top
i would say anything between 8x9.5 and 11x17 is sufficiently sized. i would say that something 1/8" thick at least is much nicer to use than thin 1/16" thick pads. if you can manage to get a 1/4" thick pad then they work even better yet. my standard sized mousepad is a 1/4 and my large pad is a 1/8. my brother has a very large 1/16 and its a bit thin (sometimes it scrunches up if opjects are bumped into it)