I'll second the idea of installing yourself - it ain't that hard. I did upgrade the anchor bolts to better quality and length to take advantage of my slab thickness. Also upgraded rest of hardware but I do that with most things. '71 F250
I also got mine at Greg Smith in Atlanta (about the same time as LDowney IIRC) just because I could pick it up and not deal w/ shipping hassle. Don't remember what I paid but I'm thinking about half of what they are now. Yeah, it's Chinese (but so are most others). I got the 10k and it does...
Also look into a simple safety switch. They can usually be had fairly cheap on ebay like this one. Even a 3-phase will work, just don't use one of the legs...
Looks pretty similar to my 25yr old Ingersoll Rand. Have always run on plug so not hard-wired but the few times I had leak issues in the lines all it took was a turn of the cut-off valve at the tank to prevent leak down/running. Of course that assumes no leaks in tank and compressor to tank...
Go lower while you still can. I had a mezzanine in my old shop that the idea was same as yours - storage of stuff I wouldn't need often. Shop didn't have tall walls so I didn't have much choice when it came to height but I frequently found myself up there crawling around or hunched over trying...
How did they price out the foam - sq ft or just eyeball it? I've got a barn I'd like to get spray foamed but don't have the slightest idea what costs may be like.
Oh, and Martha Berry approves!