It sounds to me like you hope to create generational cheap rentals for some unknown reason.

I’m planning to partner up and borrow from stocks to fund this.I’m currently in a bit of an unknown state after that.

Typically how  much extra should I budget for, for these unknowns? 

Storm sewer, storm pond, sewer lines, water access, fire hydrants, public bathrooms, surface coverage, sidewalk or bike paths, setbacks, power lines and right of ways known and unknown, road access, etc.              5.  

I can proudly say I did not spend lots of money on fancy ring tones, as I never answered my phone for unknown numbers (which you can actually set your iphone to send them to vm btw).I get calls constantly about people wanting to buy a property I have not owned in 5+ years as well. 

A timber buyer is going to adjust for: location to roads, distance to mill, terrain to log, unknown quality of wood, Owner lack of knowledge, etc.10. 

Having agreed upon SOVs, payment schedules, retainage, design documents, and well written contracts really take a lot of the "unknowns or potential problems" out of the process.

If it is not spelled out in the agreement, then they're abiding by the stipulated scope and your gripe may be with an unknown expectation or one which was not ironed out from the start.

I haven't heard any who recommend a primary business model of buying notes with the chief intent of foreclosing versus getting the owner re-performing considering the cost and time required for foreclosure proceedings as well as all the unknowns that come  along with it.

No, I don't have a local PM so that would have added another unknown variable and expense2.