The back of the house has what was a 2 bedroom, 1 bathroom in law suite that was walled off and metered separately.

My taxable income does not exceed the limit around $200k. 1.Separate books and records are maintained to reflect income and expenses for each rental real estate enterprise;2.250 or more hours of rental services are performed per year with respect to the rental enterprise; and3.The taxpayer maintains contemporaneous records, including time reports, logs, or similar documents, regarding the following: (i) hours of all services performed; (ii) description of all services performed; (iii) dates on which such services were performed; and (iv) who performed the services.

Speaking from personal experience of seeing this go wrong, I highly recommend separation between the realtor and the property manager.

The basement acts as a 3 bed/ 1 bath apartment with it's own full kitchen, laundry and a separate entrance through the garage.

So, if you're considering using one or more of the units as non-residential (rent it as a business office, for example), then it may be to your advantage to separate the residential from non-residential.

Am I responsible for eliminating mold inside a wall that separates my unit from my neighbor?

This protects your personal assets, and some people will put each property in a separate LLC To avoid a lawsuit on one rental from risking the others.2.

The real estate and the business (bar w/ liquor & gaming licenses) sold separately.

Should I analyze the deals separately and put them together or something completely different?

(that is a whole separate question!)