Yes, I have heard other people in MP use it, although I have never used it.

yes, I use an old Logitech x-52 that I've had for about 10 years now and received second hand. it is a HOTAS w/ a separate throttle collective and a lot of buttons.

My recommendations (as far as this game goes is at least 9-10 programmable buttons (all channel toggles, view toggle & mode, engine start & stop, and recovery
with at least 2-3 programmable axis for manual trimming or flaps. However even the most simple stick will help tremendously.

Before I used a keyboard controls and had a hard time with any sort of complex aircraft without gradient controls (lots of bad landings on my part w/o a stick and throttle.