Re: Impeller install
That all depends on your mechanical skills, and, or, your access to a manual.
I did mine this summer without a manual and it took less than an hour, from start to finish, with running motor, and I took my time.
I hadn't ever replaced one, nor had I watched anyone else do one since I was a kid. There were step by step instructions in the water pump kit package, but I didn't see them till I already had it all apart. I just glanced at them and went back to work.
It was easy.