For example is your 4-plex payment is $1k and you are getting more than that in rent the $1k payment could be zero debt. 

Also the rates are usually adjustable and term shorter than a 30YF.Refi possible advantage if you favor + cash flow rather than being debt free sooner, depends on your equity and amount you're looking to pull out, you might be able to take out the cash you need and still end up with a lower pmt than currently because you're re-upping for a new 30 years. 

Shoot me a DM and I can help connect you with SFR/commercial, agency debt.

If the numbers work and you have sound exit strategies for the deals you analyze you will be fine. 100% agree with @Michael Ablan in that you likely wont make much on appreciation but you can easily cashflow and gain equity through debt paydown.Closing on a Triplex in the area here in a few weeks.

You want to have a balance between debt and good payments on that debt.

I am working two (non-real estate related) jobs, in order to pay off college debt and save for my first rental property!

If I put the first house in my LLC will the debt come off my personal credit, which will help me get approved for the second home I want to live in.

It should be calculated without debt service to calculate the return.

However, the mortgage broker I use is able to count the income of my rentals against the debt.... so I continue to bump against his DTI limits, but as long as each investment makes sense and has decent returns, I can continue to buy.  

I sleep very well at night being debt free