We bought the acreage we've got now back in March and didn't have enough time to get all of our horsey project done this past summer/fall so I'm starting my list of things to do for this spring/summer. First, and most important, on my list is building stalls in our barn. Right now it's pretty much a big open shell of an area in the middle with two good sized run in areas on the sides. It was completely gutted by the last owners, floor and most of the hayloft included.

We're planning on putting in 5 box stalls in the main area--they'll probably be about 12x12 or so. We also need to fill in the floor, it used to have wood and that was removed before we purchased the place so now we are left with about a 2' to 2.5' deep area to fill throughout the entire area of the barn. Here are my questions for anyone that has experience with this kind of work:
What is the best material to use for building the stalls? We can get cedar or cottonwood trees and mill them up ourselves so getting wood isn't a huge issue, I just need to know what type is best. I've always liked the look of cedar stalls but cottonwood is much harder and tastes bad so they won't chew on it or be able to kick through it and it's easier to get. How far up should we build with the wood itself? I was thinking about 4 feet but don't really know.
How about the top portion of the stall walls--what material works here? I was thinking about using cattle/hog panels and reinforcing them with rebar or something similar. I've seen people who have used rebar and welded the rods onto a frame, which is ok, but I think it would cost more. We're trying to be as cost effective (ok, cheap) as possible while still keeping things safe and useable. How tall in total should the stall walls be?
How about doors? I've always liked the look of the sliding door but they seem to stop sliding after a while so I don't want to use them. I was thinking about using the smaller tube gates for doors, that gives easy access. Anybody have suggestions?
Now for the flooring....ugh. We are going to have to get a ton of fill for the floor. I don't want to have to pour cement so I need to know if we should go for straight dirt all the way through, gravel on the bottom and dirt on top, alternating layers of dirt and gravel or who knows what else. I've seen plenty of barns with dirt floors and it seems to work for them but I really don't know squat about this kind of stuff so I am open to any and all suggestions.
I took some pictures so you can get an idea of what I'm working with, I'll post them whenver they get done uploading to photbucket.
Thanks for all input and suggestions...I need all the help I can get!