Our pool guy reccomends draining every other month or so to keep the ground water down. Definitely before a storm! We connect 1hp motor and it drains for days.
Commonly called a well point around here.
I've never had wrinkles after New install. And have been told u can't "reseat" liner and have it line up correctly with returns and skimmer already cut out. I believe it's his responsibility if u had wrinkles from day one.