While the general principles regarding LLC ownership, asset protection, and taxation may apply universally, specific legal requirements, regulations, and tax implications can differ from state to state.Good luck!

You are not EVER required to use a property manager if you own more than one property, or for any quantity of properties you own.

To remove the snake and fix the plumbing required demo of both the units bathrooms and removal of the concrete flooring (slab).Curious under what circumstances led to the broken drain snake???!

Furthermore, is there a seasoning period required for this if it is a home I intend on occupying?

You are only required to have the property be your primary residence for 2 out of the last 5 years. 

Imagine a $2M loan not requiring a down payment.

For the tenants that will occupy the empty unit in the not too distant future I can make my own rental agreement, in particular, I plan to let them pay for the water as well, and I will set a reasonable security deposit.But for the tenants in the currently occupied unit:1) Would it be possible to write an addendum to the existing rental agreement to require the tenants to pay for their portion of the water bill?

This is implicitly required of any HML.

Just on the business level for landlords to be as specific as possible with their requirements and give detailed line item dispositions. 

And actually, there is no statutory requirement that you rent the property.