She asked to pay with a different credit card than the one on file with VRBO but whatever, that’s VRBO’s problem to deal with, we told her to call them up and ask to switch it out and she did.

The Margin is fixed while prime rate floats and its typically interest only.As for fixed rate loan cash out refinance its fixed its great but downside is you pay interest day 1 even if you have a project to work on or not.Depending on how you plan to deploy and how much you think you'll be deploying you'll pick a fixed or a line of credit.

My credit score is "good-great".

He currently has about $10,000 cash and about $20,000 in credit "Home Depot line of credit for materials."

The catch: my partner just sabotaged his credit and is self employed.

I get these lines of credit/ mortgages off my investment properties that are rented.

I was planning on purchasing a 400k MF with cash but was planning on getting a line of credit on the piece in order to handle any "expected" surprises. 

Also, it would be wise to get some credit lines just to have in case as well. 

I have little income with good credit.

It will most likely be a line of credit with a second lien deed of trust (2nd mortgage).