i built mine as more of a reloading and general purpose bench for myself. Its 36" deep 6 feet long and like 40 inches high? I have shelving on the back 12" leaving me a 2'x6' area for working or whatever. My press takes up probably 2' though so only really have a 2'x4' area. Which is plenty. Ive built an AR, clean all the guns on it, and done other things like built a computer on it.
I have carpet and can tell you it can be annoying at times. Depriming or even priming if a primer hits my carpet and i dont see exactly where it falls it can be a pain to find....although i dont care to much personally but a wife/gf might!
Fire extinguisher wise i have two small ones....they are the size of those compressed air cans. I have one mounted to my reloading bench and one sits on my computer desk on the other side of the room.