Rental income and expenses, such as mortgage interest, property taxes, repairs, and depreciation, can be reported on Schedule E of your personal tax return, regardless of ownership structure. 

@John BuschHi Christopher,A few great local options to consider are Mike Keith with A&E Construction (352-270-0399), Citrus County Handyman (352-440-3305), and Dynamic Craftmasters (352-422-5119). 

I am not seeking to charge each tenant, only seeking to remotely monitor each buildings water usage to identify costly waste/problems early as possible.

If E has any priority over B, for instance, I would not invest in this structure, given that my bank account puts me at a Class B share (side note, their Class B is a little more GP friendly on the surface, than other groups, but devil is in the detail).  

I know that the general guidance is that emergency funds aren't to be invested, but given our financial security and the fact that we already have a personal e-fund in a safe, non-volatile location, would it still be crazy/unwise to invest this 15k in an S&P500 index fund in a brokerage? 

For Conventional, you can only use 75% of the gross rent until you have Sched E history for the rental for a net rental income analysis. 

I find that internet providers, like Comcast, tend to update their technology and offerings to better speeds as customers have higher usage demands.

No such requirement for improving rental properties and deducting interest on Schedule E. 

@Angelo Llamas If your cousin rents out the property, it becomes a rental once it's "placed in service," meaning available for rent, and he must report rental income and expenses on Schedule E.

You can pay an annual fee if you want to have access and usage of CAR forms, but why would you when you can get free real estate forms from Firdt Tuesday.