Thank you in advance.With what you described, your best bet might be to cite AB-5 and make them W2/salary you.https://en.wikipedia.org/wiki/California_Assembly_Bill_5_(2019)You will find a world of possibilities open up as soon as that is done.

The plumber replaced the iron sewer line with ABS but he left the old sewer pipe for me to dispose of (which we had not discussed but the assumption was would be removed) and did not jet the sewer. 

They now own Lot A, B and C.

You need to categorize each building into class A+, A, A-, B+, B, etc.

Read up on AB 1482 before making any further decisions in regard to your current situation.I would recommend fixing up and renting out your currently vacant units at market rent and raise the current tenant's rent the maximum cap allowable for this year.

Just be sure to modify your lease so that is says, "Tenant is responsible to pay the rent for all 12 months of the lease, unless they cannot pay the rent for reasons A, B, C, X, Y, and Z, and then they can move out with no penalty." 

Because the financing is different for buildings with more than 4 units, as you may already know, you can't really use a per-unit price on a 4-unit and extrapolate to a 5 or 6 unit :(Instead of looking for comparable sales, you usually end up having to apply a market cap rate to the net income (NOI) of the property, which appraisers call the "income approach".As for what's a "market cap rate", well that's about as much art vs. science as (in some way) choosing good sales comps are.For a B area of Providence I think you'd be safe using a 5% or 5.5% cap rate, but if it was an A area like the East Side you might want to go with 4% or 4.5%.You should also ask around as I certainly haven't done any market survey of cap rates.

Yes.Class A/B are the bee's knees.

In a B or C class, a new bathroom is better than your competition's bathroom, likely.  

Specifically that handles assignments and a double close or an A-B-C Closing.