Help! Plumbing replacement

[oneBlessedMan]

I’m new here but I’m in need of some serious help. My drains keep backing up and I know it’s because the drain pipe is not graded out because they have fallen down towards the middle of the house over the years. So, I’m going to replace them. I have attached a picture of the culprit.

Anyway, it looks pretty straightforward, but I’m sure there’s a better way to route everything. Also, I’m concerned that when I remove/cut the pipes then the vent tube will fall down. I need to keep that where it’s at until I can reconnect it (see second picture).

Any advice here? Thanks!!

 

[Geofd]

its not hard it just takes some thought...the area near were your going to cut has to be hung off the floor joist by 3/8 threaded rod and copper a band or copper clevis hangers
and if its cast iron use stell clevis hanger or steel a band hangers and use 3/8 nuts to lock the hanger and rod so they cant loosen to hang off the wood you would need side beam hangers or f+m plates with 1 1/2 wood screws to secure the beam clamps....