i wasn't buying this as a start to my real estate career just to help me with the mortgage.

At first this sounds like a good thing because its a cheaper entry level but the more you own the more complicated life can get.

If your rate is low on the 5 unit, I might consider the possibility of a line of credit for my equity instead of an entire new mortgage.  

I'm interested in everyone's opinions on using a HELOC to purchase turn-key rentals for the short term and covering principal paydown across all new mortgages / loans ( HELOC ) through excess income. 

You are dealing with 2 immovable objects in HUD and Chase and you would be better off with a mortgage broker that would have options. 

Or you can pay the mortgage off early.

You could spend $2,000 a month on a mortgage instead of rent.

The down payment to acquire this sub to is $25,000. so you give them $25k, you take over a $70k mortgage and they are going to pay $165k in a few years - if you will not do this deal send it to me I will do it. 

There is a recorded mortgage and also a promissory note.  

There are several benefits of having cash in the bank/liquid reserves versus an open end mortgage (a.k.a) credit card.