Provided you are sticking to the letter and spirity of your rental agreement, you have to set boundaries People that get indignant over you setting boundaries are not worth worried about. 

It never hurts to have an additional set of eyes to look after your property.

What sets your lisitng apart?

The problem with that set of formulas is that a fixed rate loan will NEVER have different monthly payments due (your example starts at $675, then $674.25, etc.).  

You know how to manage a property.To get started, your first steps should be getting licensed then meeting with a local RE attorney so they can help you get set up with your contracts, management and lease agreements, etc.

I wonder if the change of density could off-set cost of underground enough to make it make sense.... 

I am subletting a property that I am planning on purchasing the set up where instead of any type of security deposit I am re-having the property which is necessary before I rent it out.I will have about $20,000 in expenses all before I purchased the property.

I would say get connected with a local agent and also set up with a lender that has you pre approved to make it super easy making offers.

For consulting with a CPA.As mentioned above you can simply take monthly distributions, but what is most important is how you are set up. 

Setting up your purchase money loan to allow better refinancing is advised when possible.