221g Mumbai

[221-green]

Hi everyone, I just got 221g on my stamping renewal in Mumbai. Details below:

2nd time H1B renewal. Went from F1 to H1, renewed H1 once, now second renewal after 6 years.
Been employed at the same company since 2014, however more on that later. 
Directly employed by the company, no clients or vendors etc. Never had an issue with previous stampings or petitions either.
Qualified for dropbox but decided to apply for interview.

Fingerprinting/Biometrics: Aug 31
Visa Interview: September 7

Questions asked were extremely basic - where do you work, what does the company do, how much is your salary, where is your office located, how long have you worked at the company etc. Within two minutes I was told that "I'm going to go ahead and approve your extension, you'll receive your passport in 2-3 working days". Did not even ask to see I797 or any other document at all.

Got mail on Sep 10 that passport is ready for pick up. When I pick up, there's a green slip and my previous H1 stamp is cancelled. Obviously this was completely unexpected!
In the green slip, they asked to submit petitions for change of employer from Company A to Company B to Company C. That's it. And it says submit this slip along with your passport.

Now I'm sure the only reason they wanted those documents is because I changed employers from A to B some years back. Since then I have been at the same company but they have restructured and filed a new petition under Company C (which is my current petition). And even after that, they legally changed the name of that entity (although the company and everything else is the same). My last stamp was with Company B, so they probably wanted to know what this Company C is, thus requesting change of employer petitions. Or so I think at least.

I've already collected the documents and submitted them (with passport) to the dropbox last week. Some questions I have are:

Has anyone else received the green slip in Mumbai recently? 
What was requested in the form, and what was your experience? Did they to submit passport too?
How long did it take to process? 
Did you get any other slip after?

What does the green slip signify? I have read many conflicting versions of what each color of slip is used for. Some different colors seem to request documents only, some via email, some request you for interview, some need a long list of client documents - my slip instructed me to submit passport alongwith petition documents etc. 

I've read so many different experiences with this nightmare of a process that who knows what will end up with me - could take months!

Thanks!