It's based on sq footage for business vs. personal...and then shared areas you get to take a pro-rata amount. 2) I have consumable expenses (Shampoo, Towels, Sheets, ...).

So, you generally get a lesser fraction of your property considered a rental --- lesser pro rata share.. 

Some pass through losses straight pro-rata based on dollars invested.  

If I don’t rent out the other unit  (using the whole property as primary) does that increase the pro rata of exclusion enough to offset the rental income not received from the other unit for the 3 years ( 36000) in the 3 years?

RE Taxes are estimated, usually by the title company, as the pro rata share of anticipated taxes due.

The lease should spell out the tenant's pro-rata share of operating expenses, taxes, and insurance and should also spell out how the tenant's pro-rata share is calculated.  

HPC will arrange the transfer of a pro-rata share of the 12 Bridges assets to Vista of the four short-term rentals in Scottsdale valued at $3,209,709 to cover the shortfall partially.

If you invest passively you should receive your pro rata allocation of bonus depreciation on your K1 along with the other investors.

Go 50/50 or pro rata on ownership percentage and capital contribution

If you had a year lease that went month to month on termination and it says nothing about PRO-rata rent you are entitled to a full months rent.