I'm a first time buyer.Here's what I show my clients to help them decide if buying down the rate makes sense.In your scenario, the difference in your PI payment @ 6.275 and 5.75 is $54.71.

Having a mortgage payment plus needing to pay an extra $1k/mo towards this TSP loan will crush any cashflow you had hoped for.  

They will accept the payments and transfer to you, as well as handle the paperwork (e.g. yearly 1099's, payoff statement when time comes, etc.). 

I know California is not so investor friendly due to high taxes and non landlord friendly regulation.Florida has high insurance costs in some areas?!

Texas is a non-judicial State and there is no need to go to court.

If I take those out like a HELOC how do I actually pay that loan back as I'll still have a monthly payment for that loan? 

Can you get a non occupying co-signer? 

I would be looking for something in the 200k range and have anywhere from 100-130k for a down payment. 

If you are locked in at a three-handle, I would HELOC the equity and use it as a down payment on a new deal.

By doing so, from her perspective, if you miss a payment she keeps your 70k and takes the house back so thats really good protection.