Thanks for the info on codes. Our frost level here is 30" i've been told.
I'll need to touch base with the inspector since I now plan on a slab.

The ONLY concrete I've ever done was a 4x4 slab for an up flow sand and gravel filter for a koi pond I used to have. For the filter to backflush properly it had to be level. That was about 12 or 13 years ago, the pond and filter are long gone, but that slab is still perfectly level, if I never pour another one. Concrete just has never been a priority for me til now.

I think it was John that mentioned a very slight slope so water wouldn't stand under the shed.
I assume you meant sloping to one end of the shed, regardless of the surrounding landscape? I think water would get trapped if it sloped to one side what with the 4 runners the shed sits on.
I have plenty of time to study up on concrete. Perhaps I'll gain the confidence to do it myself. I'm not a genius, but nor am I an idiot.