This is an awesome post with great photos to follow it all! Thank you Mac!
A bit late on the building permit thing!! Though getting it even after the fact could be a good thing if you have neighbors who may 'turn you in'. When we built ours, I heard after the fact that one of our neighbors tried to turn us in, but I DID check in advance and in our township, as long as it's under 200 sq feet, we didn't need one. I heard the old bat was very upset that we were legal. (this is the same lady (term used loosely) who snuck on our property and dug up a bunch of day lilies without asking. Thing is, if she'd asked, I'd have helped her do it and wished her well! Since she didn't ask, I went and repossessed them, (and gave them to a friend a few miles away!). I wouldn't have known who left the holes in my lily bed, but another neighbor took photos and e-mailed them to me... dontcha just love digital cams with zoom?
//edit to add// our land is very hilly so we needed to handle the pitch of the hill with supports of various heights.. more complicated but still the same idea.