Yay! I'm glad its working for him :)
As for the vacuum, you don't need to shake it in the water, this way is much easier and doesn't cause any splashing or anything. And yes, make sure you have a bucket of some sort to catch the water, this little thing is a beast and takes water out pretty quickly.
The way I vacuum my tank is I take 50% of the water out then fill it back up with conditioned water as close to the same temp as i can get it then vacuum once more. Once you start vacuuming regularly you shouldn't need to do it twice like that, but i usually go a few weeks inbetween my water changes (shh don't tell anyone, they'll yell at me lol). Some people leave their fish in the tank, but if you haven't vacuumed in a long time you're going to want to cup him for a little while because the tank can get really gross lol.
Skip to 4:00 - she shows the easiest way to do it