Depends on the current lease agreement and your jurisdiction's landlord-tenant laws.

One of the legal downstairs units is room-hacked, with 4 tenants living in the unit and separate rental agreements w/ the owner.  

I've decided to have 2 separate agreements and am wondering if anyone has a good option agreement to share. 

All you have to do is sign the standard agreements and receive a check in the mail every month.Negotiate a $5k down payment with a 30-year seller financed note.

IF you had your agent source the OM from them, I assume that the CA would be slightly different where the commission split would be explicit.If you have not signed any CA, then I believe your agent can still contact them to get agreement regarding the commission split.

Always do the analysis numbers and try to look at it before you make an offer or at least have a clause in the sales agreement contract that will allow you the time to get an inspection and possibly back out of the deal if you want to without a penalty greater than your earnest money.When you close on a property, right after it, get an insurance policy that will protect you if there is a loss.  

Can you attract different/better/more tenants by allowing pets.If you accept pets, insist on meeting the pets first, photograph them so there isn't a switcharoo later, and include plenty of language in the agreement about your expectations.

@Jeffery Waicak it looks like many missed that you mentioned it is your friend with the good credit, not a random agency pairing people.If you were to do something like this, I would recommend an LLC with a well thought out Operating Agreement.

And should I go ahead and make the purchase agreement with the seller to avoid this?

This realtor was very helpful, but when I went to make my first offer, it was requested that I sign an Exclusive Buyer Brokerage Agreement.