Pet Evolution

I have now trained my pet to a level 15 Dire.

From what I got from the tutorials,
This is the final evolution.

Does this mean I can put my normal build back and start doing the normal quests again?
Then I will do more damage and he will take more damage (wich pushes the pet to 'harty')
Or do I have to level it up all the way to 20 first?

Will my pet remain 'dire' if I start using my normal build again?

A pet can evolve at lvl 20, it is rare though. So you might want to lvl it up all the way to lvl 20 first.

dire is a final evolution, feel free to stand near to a 55monk at work and do nothing if you really want