Use the "passwords" feature to check if one of yours is compromised. If it shows up, never ever reuse those credentials. They'll be baked into thousands of botnets etc. and be forevermore part of automated break-in attempts until one randomly succeeds.
No. When you click into a password field it puts a password field above your keyboard like word suggestions.
It is not seamless, but it is not a pain in the ass. If you have ever used the keychain or passwords app from Apple it works like that.