Hopefully renting demand will increase due to lack of ability to buy housing. 

You do have Loopnet, Crexi, and other auction sites, but those deals have already been looked at.It depends upon your knowledge, and the ability to either deploy your own capital or raise it where you should start.

You can choose to terminate their leases and start fresh, or verify their ability to pay the new rate.

The frugal straightlaced one and the challenged chaotic one with limited ability to recognize a con, more "friends" bamboozled him then I care to count. 

It is not typical for owners to collect their gross funds and receive a bill for your fees.

Hello World, I have been doing research on "cash" offers as an investor and the results I have came up with is a "cash" offer can be consider any funding that is or has the ability to be liquidated without contingency from a bank; i.e. hard money, private money or your own cash.

Wholesaling is a great option to diversify your toolkit of potential deal exits if you are an experienced investor, but I think you should always have the ability to flip the deal but decide to wholesale due to some other limiting constraints (e.g., not enough contractors, bandwidth, etc.).

Ability to pay, do they pay, have they saved?

Pet proof the place to be best ability. 

This friendship is already destroyed.When you do finally get them out, perform a walkthough and send them a bill for every repair that you do.