Is stamping mandatory if previous employer revokes the petition

[sri1818]

I have a valid stamping with previous employer (Employer A) till Jun 20 2019. I have an approved petition with current employer (Employer B) until Apr 2021. Employer A revoked the petition with whom I had the stamping. 
I am planning to travel to India in Feb 2019. 
Q1: Is it madatory to go for stamping/dropbox?
Q2: If not will there be any problem at the port of entry?
Q3: My spouse doesn't have approved i539 (for H4 transfer/extension from Employer B). If stamping is required for us, Shall we go for H4 dropbox/stamping with just my approved petition or is it mandatory to have i539 approved document?

[luck2u]

@sri1818: FYI...

1: You don't need to go for stamping as you have valid visa till June 20 2019.

2. No problem will be at port of entry.

3. I-539 is not required, just ask your wife to attend or drop documents for her H4 using your latest I-797 (with Employer B).