@Bradley Chiakas , are you accepting payment for this service? I believe you need to be licensed in all 50 states if you are accepting payment for rendering this service.
That said, I would definitely get everything in writing so you are both on the same page. I'm not sure what your second question means. Are you leasing his rental from him, then sub-leasing to others or are you managing his rental for him?
I believe @Mindy Jensen is correct. To accept a commission/fee you need to be a real estate broker or licensed re agent working under a broker. Exception: you are an employee of the owner (typically builder/developer) and showing only their properties.
That being said, I know of lots of people that are doing just what you propose, and are doing so knowingly or unknowingly breaking the DORE laws, at lest for NY and PA. I have seen the properties these 'managers' handle, and often they are NOT being taken care of properly. (Not to say you wouldn't, but this is my personal experience.)
On to lease/sub-lease--If you want to do that, you are a TENANT and responsible for everything your sub-tenant does. Pays rent or not, YOU are responsible. If they do damage to the property, it's on you. If there is a big enough spread between your lease payment and what the sub pays you, maybe it's a deal. I certainly wouldn't do it in my own name--use an entity.
You'll have to ask yourself if it's worth it.
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