They will affect what you can and can't do and will affect the home you build (ie exterior finish, landscaping, colour, etc).

The three items above along with setbacks, landscaping and storm ponds if required dictate your footprint.Find out what the DOT's variance process is and follow that. 

I haven't as I don't really know and/or understand US real estate landscape.

I was out of state on a trip and so my sweet wife was the one handling most of the talking with the Wholesaler.When I still like to browse Roofstock I examine each home property report and statistically, 7 out of 10 homes are having problem with foundation/electric/plumbing.Property inspection helped a lot especially when the inspector is good.Thanks,

The PPC landscape is highly competitive, mastering it can bring excellent results if it aligns with your budget and closing capabilities.

All that being said to get the house out of the hole you first get your permits, landscaper silt fence your lot, then have your surveyor come and rough stake the house, landscaper grub the lot, surveyor pin the house, concrete contractor set your form boards, plumber dig your underground plumbing, city/county inspect the plumbing, concrete contractor prep the slab and dig the footings, city/county inspect it, concrete contractor pour the slab, now your out of the slab and on to framing.

You can find the statistical data via the major moving companies, and I believe Ken McElroy recommended this site for that purpose:  https://www.northamerican.com/.... 

Do you have any statistics for me on what the likelyhood is for a USDA loan to be called versus any other agency?

The next study below from Cambridge associates looked at 942 funds from 1986-2016 data and showed around 3.9% outperformance of equity REITs over private real estate with median leverage between 54%-60% so not as high as individual house flippers but still with significant leverage:There are many other studies in US and also by EPRA out of Europe in developed countries as well as many academic studies, https://www.nareitphotolibrary.com/m/750b587aba063147/origin...and they mostly all agree that on the whole, on average, for the Average investor, that private Real Estate investing is statistically worse than stock market in US by about 2% and worse than buying equity REITs by around 4%, over last 20/30/50 years. 

You could also add landscape ties along the bottom, should they try to dig under it.