I would start calling smaller banks and credit unions that may be portfolio lenders as they may be more flexible 

You're on the right track with getting a 3.5% FHA loan for the first one - you only get the chance to use it once so use it wisely.  

They offer the "close in 7 days" deal, and get me a underwriters dissuasion before looking for having a property under contract which is the main reason why I choose them.I have a about 10% down, good credit score and low debit to income. 

Conventional will be depending on credit, seasoning, LTV's, DTI etc. 

,My name is Jason and I looking to get more education on the options, requirements, and overall strategy for obtaining unsecured business credit as capital for investment in real estate.

I used mostly credit cards and borrowed money for the purchase down payment and rehab cost, and now that we're finishing up I'm doing numbers on payback and the next property.I want to keep up momentum and start the next project soon, but by my count, it will take me somewhere around 5-6 months to pay off all the debts I incurred in the process of purchasing and rehabbing the house (not including the mortgage). 

I just ding their credit and move on.

Income is the number one thing to consider followed by credit history.

From what I have seen while looking at sample tapes, FCI exchange/other websites, and other comments; is that performing notes cannot be bought with that much of a discount (but I haven't seen what local banks/credit unions provide in their pools/tapes).

Also, if you have acquired the line of credit but haven't actually withdrawn the funds most banks would still be OK considering that as a credible source of down payment without having the actual found in your account as cash.