Make sure they have verifiable income also so you know they have the ability of paying rent.

@Marco Santarelli Though southern California may not have the cash flow of some areas, we do have solid appreciation and the ability to maintain value that cheaper areas don't. 

With ListHub, broker members will continue to have full control over their syndication, with the ability to opt-in/opt-out of syndication or specific publisher websites in the ListHub network.

 Ability to pay, what is the borrower's ability to pay?

I assume that the reason for the HELOC and cash buy is to give you a stronger position when negotiating purchase price and the ability to act more quickly vs. obtaining financing.

People do say that apartments are harder to sell compared to single family homes, but that's just because with SFRs you have the ability to sell to either another investor or to an owner occupant.

That is a very common question and always falls back into what is your goals and current financial abilities.

assuming that I need ANY of the rent in order to make the monthly bills of the property or should i only be looking at scenarios where i can cover all monthly costs regardless which would severely limit my buying ability? 

I've had several partners, and sometimes i've questioned their ability to make decisions.  

Putting an age on someones success or ability is very limiting and could stall your success.