installing a new bathroom sink, should I replace the water valves? Raise the drain pipe?

[mattkime]

Here's my current project. I removed the old cracked sink and I'm replacing the whole setup with something at least 50 years newer. I'm tempted to replace the water valves in this house tend function poorly after half a century. I also want some storage in drawer form under the sink so I'm considering raising the entry point of the water valves and the drain. Yes, I know this will be work but I've yet to determine whether its work I'm willing to do. This is a first floor bathroom and I have access to pipes directly below in the basement. PEX seems like a reasonable option for replacing a length of copper, although I've yet to determine the correct way to terminate it at a valve - seems like it would need to be mounted to a stud. The drain pipe would be the more difficult part - I think its iron, definitely threaded...maybe it wouldn't be so bad to join it to a short length of pvc, just haven't thought it through yet. Obviously this would involve some drywall work but I wouldn't mind it. This is an exterior wall, if it matters. And I can take my time on this - we have other bathrooms.

The new sink will sit roughly inside the outline of the old one, minus the parts that hang down lower on each side. The former sink's basin also came down a number of inches. The new sink will be higher and shallower overall.

Oh, I'm curious if there's a standard height for water lines and drains. Google didn't reveal anything.

Anyway, tell me why this is stupid, aside from the obvious. I know its more work than strictly necessary but I want to ensure that each step is manageable in itself.