There is no reason for Unit A or your responsibilities for Unit A's portion of water to be mentioned in Unit B's lease and I'm assuming it is not.If you take Unit A out of the equation, that line literally reads that Unit B is responsible for the water bill, except for the first $100.Though if you can get in touch with the previous owner, it would be helpful to know the history of what has been done. 

We would also have another $60k to invest each year after maxing our all our tax deferred investments.We’ve invested a portion of our SDIRA into an LLC that is purchasing and selling land.  

Much of the time the equity is split anywhere from 60/40 to 80/20, with investors receiving the larger portion.

Further renovation will be negotiated if we find a tenant interested said portion as an art studio (option to convert to live/work mixed use space) to pay the land contract for the next 2yrs. 3-5yr plan: potentially keep previously mentioned small portion as a rental for income/ reno budget.

If the owner is paying for any portion of it, I write a specific dollar amount and that is a hard limit.

What can be deducted- prorated expenses based on the square footage of these expenses or other reasonable method (usage) can be deducted:  Mortgage (If you use these expense as home office deduction, you cannot take the same portion of the expense as itemized deductions.)

If you were to buy it, at least a portion of your monthly expenses would go to paying off principal, and you can take advantage of the tax breaks for owning property, and market appreciation.

If you are going to use property management, you can ask them for their assistance for the inspection portion.

I just want to make sure once I receive my portion, I’m not missing anything.

On your sellers note does it stipulate that a portion of the rent payments would go towards the principle purchase price?