I have about 50k worth of capital and the bank is offering a rate buy down from 4.5% to 3.875% for 3.25 points.

I’ve been told that banks in TX are not able/willing to do a cash out refi on investment properties.

Chris -   some lenders  will not let a HELOC in 1st position.....so watch for this …...most lenders  will not do helocs on  investment  property only on primary residences  ( there may be some exceptions )   …..if these have 2 adjacent tax lots - you prob wont find a lender to lend one loan on both  properties  …..I would recommend  checking with the smaller banks and cedit unions in your area ( n Pierce / s King counties ) good luck

Talk to the code officer ahead of time and explain what you are doing and you want to do everything right. 

Does anyone know of banks (or if it is even possible) that would appraise a 1-4 unit rental property based on cashflow?

Can I use someone else's money (that wasn't gifted or loaned to me) for my down payment on a bank loan?  

There is not much I can explain in a post, but $20,000 in one is completely different in the other. 

They are non-banking investors looking for someplace to invest their money.

We have clients using private banking systems to gain additional revenue on their rental property.

So I found a bank, which I wouldn’t use again, and got pre-qualified.