-Jeff The whole thing is calculated and then you will deduct the percentage in this case 50% assuming he actually uses it.Otherwise by the sq ft of the room versus the sq footage of the whole house including basement.

They make a percentage of what every presenter sells. 

I know this will very from deal to deal but how much cash flow will you get on a home you are financing and renting out. is there a rule of thumb or a percentage that you can expect to get.

Sounds like you're at the top-end, pricewise for a duplex though, with some variables dangling out there that are a little concerning.

Jays comment in regard to housing quality is likely one variable that differs between us. 

Given average rents of $1,500/month, it would be worth it to spend $20,000 to install a solar array if it can help you reduce vacancy rates by even a single percentage point.

But there are too many variables for any body to give an answer on what works.

As the property manager in Maryland, can I charge a percentage of the security deposit and the first month's rent as a fee for services,

Or add a variable "heating charge".

Was nice because building purchase was next to nothing out of pocket because the loan was to cover a percentage of the building acquisition plus build-out of one of the commercial spaces in the building.