Good call, getting multiple bids is definitely the plan.

Both tenants just moved out.I just got a bid to correct the foundation the right way by the most reputable company I could find (full underpinning, 60+ piers) ~$65k, plus costs of repairing drywall, paint, vacancy, and new flooring.

Needs gutters, full kitchen and bath, floors, paint with some drywall repair, windows, front porch and the deck on the rear is pretty poor as well.

I will also be doing all the cosmetic things you can think of: paint, flooring, bathroom reno, kitchen reno, so I am open to carpenter or design suggestions.  

If the “all water off for 10 minutes” plan is unworkable. 

Cut out enough of the old floor, dig and pour a raised foundation? 

We added value by updating the kitchen, bathrooms, and flooring, while also improving the property's curb appeal.

New flooring throughout, new paint in and out.

We purchased it with the intention of living in the Ground floor + BSMT apartment and renting the 2nd floor apartment.

Of course, the floor plan has to be conducive to this.