Bathtub drain schedule: to keep or to replace?
I've worked with those fittings and they are top of the line. I wouldn't be replacing them based on what I see in the pictures. You might want to remove the rubber gaskets and replace them. You'll need to stop by a plumbing supply store to get them as I doubt your home store will have them. I'm not sure what's on the other side of the wall of the drain but it's always smart to leave some sort of removable panel (you can tile it) so you can get to the faucet and drain in the event something goes wrong.