Is it out of the ordinary to ask to do a walk through with a contractor so that I can bring some concrete numbers to my buyers?

in my mind this is something to flip to someone who can actually close it and operate it.. and I am surprised an owner got this far with out vetting the OP as a real buyer.. 

Basically I need to come up with a system that makes sense with my budget and the time I have.

I’d keep it very basic with pressure treated framing, plywood door, and mesh chicken wire between the units.  

I'm not saying it isn't a good deal, I'm saying how many potential buyers can fund a deal like that?

RE agent answer the calls , show the house , and collects applications. does some basic screening from his point of view , more insight you get from the agent per applicant is better for you6. you get the applications, do your own due diligence with your own set of requirements (who knows you better then yourself??)

I won't skip over that it was a bit boneheaded on my part, but it basically came down to that I can calculate principle and interest given the loan amount, term, and interest rate.

Just sell it with a quitclaim deed or do owner financing with your buyer.

For a decent quality note with a decent yield, there are a multitude of buyers at any point in time.  

I want to get in the rental property business with the 4plex etc.Which books do you recommand for get the good basics?