Hello and welcome to BYC, glad you could join us!
1.Well I think you should have the coop on stilts for one thing so that its harder for mud to splash all over (then it rots quicker) the coop plus it will only be a small coop so it will be less money cause treated wood is expensive!
2. You will probably only need a 4ft by 5ft coop because you won't have many chickens right!?
! Great to have you aboard. Ah, coop building - I remember those days - fun and anxiety rolled into one! I agree with 1muttsfan about perusing BYC and the all the great coop suggestions, models, and ideas. Best of luck to you!