Others prefer individually picking vendors one at a time and building a more complex but also more specialized team.

I would prefer 4 doors in one property making $14,000 a month versus 20 doors with an average rent of $700 each (presumably across 5-10 separate properties).

That is the preferred method.

I live in Cary though so probably would prefer somewhere closer to Cary then Durham

This is true for the units where people will live in, kitchens are more of a capex cost but after you done you're units you have an idea of you're rental yield (preferably 1% per month) is and can accordingly decide the expenses.

 $20 to $25 monthly insurance.Most investor prefer 30 years instead of 15 years mortgages to have more leverage.  

(I prefer Dallas over Austin right now).

I prefer RentecDirect as it is more user friendly in my opinion.

I am offering the limited partners a preferred return plus 50/50 of the financial benefit in the property, I.e. the cash flows, appreciation, and depreciation benefits.How do I keep it so that I am the only personal guarantor while keeping my investors interest secured in the property?

I think the right answer is based on your personal preferences, goals, skills, abilities, and resources.