If yr gonna be a diy plumber (like me), make sure you know 2 things:
1) How to sweat copper (assuming you have copper water lines)
2) How the plumbing vent system works.
IMHO, diy plumbers (like me!!!) are intimidated by 1 and underestimate the importance of 2.
If the entire wall is going to be concealed with cabinets, you can run the extensions (drain, water) outside the wall. Keep proper pitch (1/4") on the drain to the new location. If the distance to the new location is short enough(check the requirement) the old vent might be sufficient for the new drain.
IMHO, this will be a lot easier for people like u and me. The alternative is to open the wall and locate/tap into the dwv behind the wall. If those lines aren't conveniently behind the wall, it can get complicated - especially w/the vent.