While this forum is intended to help us DIY folks with plumbing problems, there comes a time for most of us when we have to realize we are in over our heads and that there are limits on how much online help we can get for major jobs. It often takes someone one site to evaluate the task. It really looks to me like you have reached the point where the best advice is to hire a plumber. On the positive side, it looks like you have done most, if not all, of the demo that needs to be done so that will save some $$. I hate to pay a journeyman's wages for doing grunt labor. Point is, you could struggle with trying to DIY then find that you made an error (or six) and the job won't pass inspection so you have to tear out and redo. There goes the $$ you are trying to save mom not to mention the time spent with a torn up house.