Two of the properties are our primary residences.

The question I'm having a hard time with, is: since I'm a renter, I don't know whether to invest in my primary residence first (single family house) and then look for real estate deals, or if I should try to get my foot in the door with a 2-4 unit first. 

That in itself will let you know if the deal is still worth pursuing.You may get a voicemail of the primary contact so be very specific as to the reason you are calling and the information you are seeking.

If the rental property is a good deal, see if your bank will refi your primary and allow you to cash out 15k for a down payment on the investment property.  

I have these in my primary.

There is a clause about the tenant's maintenance responsibilities that says the tenant will keep the premises clean, sanitary and in good condition.

We ended up buying a primary residence instead of a rental, so we didn't require legal assistance at the time of my original post.  

Personally, I would rather have my rentals in worry-free condition than my primary residence. 

We just want to know if we can sell and use for down payment for a primary resident without getting half the profit taken away.

If you have a primary title company that you use, ask them if they would be willing to run reports on the properties you are bidding on.