Since you are light on labor and wanting to get done quickly - hand digging the foundation and hauling materials by wheel barrow is out. A small farm
tractor with front end loader and backhoe works well to do the earthwork (Kubota L series, John
Deer 5 series, etc.). This kind of tractor is about 6 feet wide and maneuverable so you probably would not have to cut
trees down. Put down scrap lumber or planks along the path to prevent soil compaction. You could probably rent a machine that would work.
To plan the foundation you need to know what the frost depth is in your area. A call to the building permit authority in your area
should answer that one. Then you need to know what soils are present at the site for that depth plus a couple feet. What kind of material is found will constrain the foundation choices somewhat. Most soil conditions can be worked with. If you are trying to minimize how much material is brought in - a pier foundation would probably be best, but that would make the in floor radiant more difficult (at least a mass floor style). If you accept more earthwork and ferrying materials your option expand (rubble trench, footer/stem wall).
