When you learn new tricks better to practice it in one place. If you landed the trick few times you can practice while moving.

I would say, practice it while rolling so you can get the feeling of pop shuvits. Just remember keep your shoulders up, all you balance is in your shoulders

It’s better to do it how you prefer

Whatever feels better

It’s always comfortable to practice in one place to help tweak any minor problems you notice. I say once you can at least land the truck clean more than 5 times (Just my opinion) then it’s time to start doing it while moving.

if u are good at while in one place you can start with moving, first start slowly than faster and faster you must practice