Within reason you can get almost any interest rate if you meet minimum qualifications for that lending product, the question is what is it going to cost.

I did a pre-qualification with a lender who provided me a rate once the property was finalized. 

I have a FICO score of 740 but my oldest credit card is 6 months,  I know your credit score is important when applying for a loan, will I qualify for a loan with a short credit history of 6 months?

I would start by asking them for a pre qualification for the type of building that you want to buy and then shopping. 

Not sure on U.S lending policies for down payments.Seller financing allows less than 20% down and no qualification.

I have qualification standards in place now and don't just rent to the first person that comes along, and I especially won't rent to family, whether I think they are responsible or not.

If it's a larger organization, feel free to inquire about their different staff qualifications.2.

What are the qualifications for a blanket loan like this or is it also a benefit from a relationship with your lender?

If it's a larger organization, feel free to inquire about their different staff qualifications.2.

Anybody searching the MLS or any other site like zillow you arent going to find much but at market deals so you are going to have to get used to negotiating or having a qualifed agent to negotiate for you.