If the 1st forecloses, they can bid at the sheriff's sale up to the combined amounts due on both 1st and 2nd to ensure they either retain the property or get a full payoff.  

You need to ensure the property will still preform.

Correct me if I’m wrong, but from my understanding, their proof of income is restricted to ensuring their net income is equal to or higher than the rent.

I think the reason for the deposit to help ensure the tenant fulfills the lease.

You should look up the home to ensure that it wasn't recently sold.  

In time, I will shift over to wrapping my commissions into the deal rather than taking them at closing, but this keeps my income and sales volume simple to track as I work to grow both.My concerns:-I want to ensure the protection of my partner's capital both when liquid in a bank account as well as when deployed on a property.

But it is important to establish yourself in one area before diving into others to ensure that you are as focused as possible on generating great returns on that specific strategy. 

You could make that stipulation as well, to ensure it is done the right way.

To ensure I understand them all they are1. 

I’ve used leverage to acquire a number of properties and I ensure they all at least break even after expenses and mortgage.