Quote Originally Posted by mn_nobody
hire a professional, this work is way out of scope for a DIY. This is plumber grade material.

I have to laugh at this remark. It is a simple job that I could have done before I became a "Professional"
Coach says the truth. Make sure you support the pipe with riser clamps.
The Rubber flexible connectors are of two types. You have the simple connector which is commonly referred to by its major name brand (FernCo) and has 2 hose clamps on it. I recommend you avoid these. Use the No-Hub band connectors (rubber connector with a metal shield and 2-6 hose clamps) and only use these at your transition points. Make sure you use schedule 40 PVC Pipe for the new material. The Green pipe is not rated for the job you want it to perform. The Gray Pipe is more than likely Schedule 80 and much more pipe than what is needed.

As coach says the snapcutters are easy they are but even a "professional" can crush and old pipe with the snap cutters. When you cut the CI by the concrete floor I recommend you use an abrasive tool such as an angle grinder to cut the pipe. This will ensure you don't destroy the pipe and in turn have to do more work than you want. Make sure you use proper PPE (personal protective equipment) i.e. safety glasses, face shield, leather gloves, etc when grinding on the pipe.

Leave the support on the pipe you are not removing, it will be better for everyone in the long run.

One more thing. Selling a house as-is is fine but make sure you disclose what you know regardless, because in this day and time as-is doesnt necessarily protect you from lawsuits.

And frankly if it was me and I was selling the house as-is I'd leave it for the new owners. No sense in spending money on someone else's house.