My pressure tank is leaking ,I tried putting air in the tank,but it won't hold.Does anybody have any tips on replacing a pressure tank.Should I replace the pressure switch while i'm at it?

Hello all my first time using this fourm, have been reading the post and this seems to be a very knowledge and helpful fourm. My projest is this I have recently been having my basement floor drain back up it was always clear by the time I got to it and only evidence of water damage left behind, I called a plumber several for explanation what i got was this from all; it was the trap at the front of the house and it needed to be removed as this was old code and should be replaced with a t connection, so I did this I cut the cost in half by digging and backfilling the hole with a friend and replaced to the city line olny to find that there was no trap there!! There was still a crack old clay pipe I replaced with new PVC upstream and downstream cleanouts. After the clean outs were installed I cameraed the line to see their was blockage and when i reached down the line I was pulling out boulder ( golf ball or larger) rocks the pluber told e this was caused by collapased pipe. So I am going to break through the concrete floor and replace the pipe with PVC? I have no way of mapping the job so was going to start at the drain pipe and follow the route it takes. I a looking for any feedback in terms of what to expect things to prepare for and any other tips and straggadies. Thanks for your help in advance Vincent