Numbers don't lie...don't argue with them or you will lose.

Hard to argue with J Beard answer.

One of these connections is a cousin at let's say ABC investments. 

Generally there is additional language that if another brokerage re-listed the property and a buyer or contact purchases that was not a contact from when it was initially listed then the first brokerage is not due a commission.Sometimes in these cases the brokerages will argue back and forth over who was procuring cause to affect a sale.

I can't tell you how many times people on these forums just dig in and want to argue.

If so, I'd argue I would need a finders fee for getting the deal, a % for accounting etc.

Yes is a no brainer, no is much more difficult to argue.  

I haven't tried this, but maybe it's best to advertise the lower rent and then tell a prospect who is interested in the house that there is a "fee" for lawn care, at least in the warm months.Pet rent is better than a pet deposit, because that way you get some money for the damage pets cause without having to argue with the tenants about it when it's time to return or keep their deposit.

I recommend you read "The ABCs of Property Management" by Ken McElroy. 

People can argue all day long that Cleveland is turning around, but people have been saying that for about 20 years and it's yet to have started.