Can i ask what will be affected by a class change like the one in the basement of college? the level of my character resets back to 1 and no more changes

If I give the character boosting items will it be reset after class change?

Hi.

1. The characters will get small boosts to their baseline stats, as well as new skills at 4-5 level iterations. Many of which will cost Aether to use, but also be more debilitating to enemies.

2. Yes it will. 

Is there only one class change in the game? does Quartz have a class change too? i want to know coz i want to use the boosting items.