If they don't pay it in full, then you continue to market it and offer it to the next qualified applicant.

You'll also pay income taxes along the way on the operation of the property.

I have experience raising capital for down payments if you are prepared to pay investors at this level.

Remember that once you purchase the property you are paying debt service, property taxes, etc. before you are even shovel ready, and during.  

Is there a way that I could submit properties to someone and pay them for doing the comps for me? 

Haven't seen the other two come to fruition...or if they have, I haven't found out.Demand might be really high right now, but it would likely be dominated by people trying to find someone to pay the full contributed capital for worthless positions in failed deals. 

I can pull a HELOC on my investment property in KY, pay outright with cash or finance through the installation company.

So in addition to what Steven said about track record and due diligence, investors should pay close attention to how the capital is structured.  

Maybe there are some things that i should pay more attention to, anything I should consider/calculate upfront which for other investments is not necessary?

To add insult to injury, every company I’ve asked for a quote based on the quote I got from the first vendor, wants me to pay another several hundred dollar service fee to come out and look at it themselves.