Once all the plaster and lathe was removed we discovered that our main stack was rusted out.

We always had a slight sewer smell in the basement but thought it was just the sewer line on the road outside. (city living, old pipes)
After a lengthy conversation with the fiance we decided the main stack was over my head and with the risk of not having working plumbing if I break something on New Years Eve weekend. We got a plumbing who was able to replace the stack from the basement to the room above the bathroom.
Everything they took out:
So after everything was inspected and approved I was finally able to start rebuilding.
Built a bump out around the 4 inch stack, floor to ceiling:

Repaired floor under toilet, previous water damage destroyed floor and sub floor. New 3/4 OSB to match old t and g floor, and then 1/2 hardibacker for eventual tile.
Life got a little better once the drywall started going up:
All the drywall was 1/2 Mold and Moisture Resistant
Also got the hardi up for the new shower tile.