If he funds the purchase and repairs, I will do all the work (meaning some demo, finding/scheduling/managing contractors & projects, etc) we will spit the proceeds.

Demo has already been done but house is full of demo related trash.

However, once a GC dug deeper for a bid, discovered stucco issues made worse by lead paint, potential roof issues, electrical upgrades needed to at least the panel and connection from street, and added the cost of plaster and lathe demo as opposed to drywall, the rehab estimate came out to $85-90k.

What kind of demo can I expect?

We demo it and build a new duplex there.  

When I've demoed plaster, I put like 15 lbs in each residential garbage bag with other garbage till it's gone.

They will also do a demo with you in which they walk you through the site as well as send you a couple different styles to look at.

Hire college students to do the demo and I'll bet some of them can do most of the repairs.

I had planned on giving $100 off the rent but after 2 days of demo and one more to go, I realize that it’s going to take more than that.

The tub was the type that also had the side walls as one entire piece so along with the tub that was cut out was the walls as well.I contacted the home insurance and was later told that they were unable to cover any costs associated with the replacement because it was considered "over a period of time damage" and not sudden.I was well aware of how to demo all of the old tub and to clear out the area but after that my youtube education began.