I assume that even though there are a few steps of contract relationship (me to designer to them and maybe to a sub beyond that), that I still would own liability in any sort of event. 

They wondered why these sorts of incidents simply wouldn't be claimed under the general liability coverage of $1M.

@Nathan Frost- correct -the " interest " only payment  is often made  monthly along with the  monthly taxes and insurance so the only thing missing from this  sort of payment  would be the  principal  amount that  would be  required  on a normal amortizing loan  (  which isnt a huge  amount  ) 

Be sure to advertise exactly what SORT of charging your property offers as there are like a dozen possibilities.Everything past that is speed of charge or dealing with billing infrastructure. 

The majority of mortgage borrowers today have rates below 6%.This means that sellers have to be VERY motivated to sell. 

I have researched the business and I have contacts and connections like family friends who are contractors/ have done some sort of real estate fix and flip.

I would go with a company who has multiple properties under management (ideally over 500 to really get the benefits a scale, think cheaper maintenance visits, experience placing tenants, lots of investor experience, ability to find deals within the brokerage, massive marketing channels for properties, systems in place to handle problems, experience handling a massive amount of problems, discounts for bringing multiple properties to manage).Also, make sure your property manager is motivated, experienced, and growing! 

We like them and want to try and make this work, but wonder what sort of incentive they have to get our rents up higher.

I could charge an additional fee to have access to it, and have them sign some sort of waiver indicating they accept all risk and won't sue me if they hurt themselves.

You will need a real estate attorney who does this sort of work, your CPA needs to be involved and it sounds like a lender.