Can you suggest me.

1. Is it Ok to change designation on new AC21 when changing the employer while working on EAD. My I-140 had designation DESIG-1(lets say) and now can do AC21 with DESIG-2 when changing the employer?

2. I just crossed 6 months on my EAD and i had 6 more months validity. With this situation, is it ok to change to employer or will i get any issues when i go for EAD extension after new 6 months ?

Thanks..