"So I comfort myself that Christians are ignorant and stupid enough to believe in prayer, so the rest of their beliefs must be absolute ignorant garbage too."

Exactly.

How powerful is a God that has to be told what "he" wants, and apparently constantly, and seemingly without exception?

Apparently, less powerful than every WalMart cashier and/or greeter, who feels their blessing ("Have a blessed day!") is more meaningful than that same treatment from God themself ("May God bless you.")

But then, they just do as humans tell them to do. What could possibly go wrong?