I would try to keep the coop on high ground. When leveling the site, don't dig down, build up.Still looking at plans for a coop. Working on leveling the site, our backyard is all downhill! Would appreciate thoughts on building a coop.
Put large overhangs on your coop roof and use gutters to divert rain away from the structure.
I like a fully predator proof run that is attached to the coop so the birds have 24/7 access to that larger space.
I have had a raised floor coop and a walk-in style and would only recommend walk-in style. I also highly recommend poop boards. I built my new coop and moved the birds in last Easter and have yet to need to clean the bedding out. I'll do it when the weather breaks and clean the entire coop. The coop stays clean by having that 24/7 access to the run and by sifting the poop boards every morning.
Consider converting a shed. That is what I did and it works great.