H-1B to H-4 COS & H-4 EAD

[Michelle]

Dear attorneys,

I am thinking of changing my status from H-1B to H4 and get H4 EAD card based on my husband's H-1B and approved I-140. However, I have two question before moving forward: If my COS (H-1B to H4)  and H4 EAD applications are pending and my employer withdraws my own H-1B, what will happen to my COS and EAD applications? Could I still stay in the U.S. without working and wait for the approvals of my petitions? 

In addition, when COS is pending & my employer forces me to leave U.S. for a business trip, what will happen to my COS and EAD applications? Thank you!

Michelle