Your property seems to have some attributes that set it apart from others which would make finding comps difficult. 

Please keep this in mind:The first thing you need to do to become successful is adjust your mindset accordingly.

All my tenants pay directly into a bank account that I set up just to collect rents.

I'm expecting the HVAC/water heating to be a much more significant project, as there are a lot of questions I have that I cannot answer about whether I'd need to expand the gas service or electrical, whether I can run small-duct high-velocity in the ceiling easily or possibly along the ceiling inside the unit instead of in the walls, etc.If possible, we also would like to install in-unit washers/dryers in the first and second floor units.I don't know if any of the above would require expansion of the gas or electrical service to the building, or how I would go about setting that up.

He went back into the unit on July 4th and set off fireworks outside and inside, had a noisy party, vandalized extensively, got arrested by the police, and made the local news.

If only for the purpose of negotiating and convincing others to buy based on your speculations of what you can get once built out. i.e. if lots are small and set backs are large then it might only limit those lots to the SFR or really small duplex instead of a 4-plex. 

Hi - first-time landlord here setting-up the lease with a tenant for the first time.

It seems the dynamic has been set, and unlikely to swing in your favor.

OrIf the property is acquired without tenants, can this parking spot extra charge be something that can be adjusted month to month (maybe only some months the tenant would like to use it, and maybe the demand increases with more tenants).

Recently purchased a property with (2) garage apartments. 1 currently has a resident and the remaining apartment is being slightly renovated to make it suitable for rentals.Being that I personally mortgaged the property, should/how can I set up the rental portion under an LLC?