Galvanized pipe life expectancy
40-50 years is a fair lifespan. I've seen plenty of houses with galvi that was 60+ years old without it failing, the real issue to me is if you want to wait until it fails to replace it.
Not greatly accelerated the process, no.
Yes.
Potentially and at decent expense. It depends on the size of the water service, condition of the piping, and access point.


If you're re-piping your house and don't mind them digging up your yard, a water service replacement is a good idea. It should be cheaper to do it all at once rather than to do them as two separate projects.