Don’t believe that you can get accurate rehab estimates using some arbitrary price per sf.As a simply example, 2 homes, model matches sit next to each other.

-My neighbor asked me flat out if I can increase my offer to match an offer that's 5k over asking (assuming we'd be able to do the entire deal with 3% commission fees and they'd be getting offers $5k over asking from strangers)-They do want to sell it to me over a stranger since it offers some perks for them to return to the area and stay at the house since I'd be doing STR anyway and he could rent the house from me when he's in town for work.Is it rude of me to ask my neighbor what his current loan balance is and his interest rate?

Maybe it''s old fashioned pilot light equipment (that needs a match to get going)..

Then find ways to network with other investors in your area, build relationships, and start a partnership only when you've confirmed they are a good, safe match. 

That way you can match up one individual lender to one property, the lender gets title insurance and is named as a mortgagee on the hazard insurance, and you sign a promissory note and whatever the lien instrument is in your state (mortgage vs deed of trust). 

They just need the Articles of Organization to match the 401k, essentially saying there must be an LLC, to open the bank account.

So, if you are looking to borrow long term you would be better to maturity match and get a fixed rate second lien for the down payment funds.If you were going to use the line of credit to purchase in cash then refinance into long term debt paying back the line, then you could rinse and repeat, the variable line would be the correct vehicle. 

I'm confused on why the monthly payment doesn't match. 

We run a full credit/criminal and are looking to verify their identity and that the addresses on the credit report match what they reported to us on the application, credit score, payment history, number of open accounts and amount of debt, collections and judgements, evictions, etc.You shouldn't run a credit/criminal and just look at the credit score.

If not permitted and you apply for a conventional or government backed loans the lender may ask you to tear it out and return to match the zoning.