Here's a copy and paste directly from the site: There are two types of loans: general purpose and residential (for the purchase of your primary residence).

I'm currently in the process of fixing up my primary residence in preparation for an appraisal to use for obtaining a HELOC.

Some banks require 6 months before you can lease or refinance- so you have to live there essentially as a primary residence for 6 months.

Our next purchase, a SFH, we purchased in our LLC’s name and paid $10k cash for it at a county tax auction.We also each had former primary residences that we’d turned into rental properties.

Most of the credit unions I spoke with lend at prime rate or even below prime rate if you go with a lower LTV, however to get the amount of credit I wanted I decided to borrow up to 95% LTV of my primary residence 

If you can lease it quickly, you know the market, you know how to get to restaurant decision makers locally, then it may make sense to do it yourself; however, if the leasing function cuts into your time for your primary job, then probably makes sense to outsource it. 

When buying a primary residence, there is no limit of financed properties with many lenders, although some are still going to have overlays and limitations.On your second question yes, you can always pay your loan off with cash, or pay down your balance, and later refinance. 

FHA loans for mixed use properties are absolutely available for primary residences.

The key difference is that in mortgage I'm forced to structure it, because that's what's due.Additional info 1 in case it matters: it's actually on my primary residence.Additional info 2 in case it matters: the balance each month is roughly $4500.

Having said that, if you don't have a primary residence yet, you could look at a multi unit and get started with that.