I have a friend who works for a well-renowned construction company in our town who has offered to be our general contractor at a discount (only charging us 8% vs. the standard 15%) and "teach me the ropes"/make the right introductions so that I can repeat this on my own in the future. 

It's a great market and I'm sure you'll do well there.  

It was a learning curve for them but well worth it.

Like @Jeremy Holden said above, sub2 could be a good option for you, he's a great resource to lean on in this market as well.

I’d like some information on rate buy downs.

Desirables: 8 min walk to trains to NYC and 2 parking spaces.I feel the property was not built well and future leaks are inevitable. 

What information should I provide so a possible investor can make a quick decision on whether it would fit in their guardrails?

If you discovered something he wasn't aware of and inform him of it, it becomes part of the disclosure process going forward now. 

We're in with them on a deal in Atlanta that has gone as well as can be expected. 

Quote from @Dan Flannery: Well done!