I wanted to write a brief note concerning my wife's experience in Mumbai. She received her visa and is now with our son and I in the US (after a four-month absence!), but I thought that perhaps someone might benefit from her experience at the consulate.
1. Her appointment letter never arrived, which is not especially unusual. It arrived in the US, and we scanned and sent it to her, but it turned out that it would not really have been a good idea for her to try to use the scan. In the event, she collected a copy of it from the window at the embassy on the day she came for her medical exam, although it is worth mentioning that the line was very long to get to that window. The staff at the window were very nice and helpful, and said that it was good that she was collecting it, as it might have been problematic to try to use a printed scan of the letter. I would suggest that if anyone has not received their letter and doesn't have a lot of time to spare like that, it would be wise for the USC in the US to courier them the copy of the letter which they received. She was able to submit her documents at the VFS office without any problem.
2. When she came for the interview, she was questioned by the clerk who took her documents, who made a number of insulting and unnecessary remarks as well as misinformation. When I called the State dept and asked about this later, the person I spoke with sneered and said, "She was just a clerk. She probably didn't know what she was talking about." It's good for those going for an interview to be aware of this, so they aren't unnecessarily rattled just before going in for their interview.
3. We got 221g'd because we needed to send a couple of documents which hadn't been included to the NVC, and we scanned and sent them by email for her to print. They needed originals. It was a major pain in the neck, but on important documents they need *original* signatures. I know, I know, sounds pretty stupid to have tried to send anything in that way, and to be frank, it sounds stupid because it was. My bad on that one.
3. When she returned with the documents (now couriered) to her!), the person at the VFS counter (different from the person who had been there earlier) demanded a document that *no one* had even mentioned earlier, and tried to send her away! My wife argued that she had brought everything she had been asked to bring, and that she needed to receive her documents *NOW*. The lady's response was a doubtful, "Well, we'll let the consulate decide." (which, I suppose, is the whole point, right?
). 3a. Important Note: As far as possible, don't take anything with you to VFS accept what one needs to submit. My wife went alone the second time (from another city) and had her backpack with her. She left it with a woman who said she was waiting for her daughter, and when my wife returned, the woman was gone, and so, apparently, was her backpack. She was then scolded by the security guard, who went on and on about how it wasn't their responsibility to look after her backpack, that she shouldn't have left it with that lady, etc, etc. After waiting there for a good half hour trying to figure out what she was going to do, the guard brought out her backpack, which it turns out the lady had left with him to give to my wife! He was going to keep her backpack!
4. The visa was issued several days later; I was able to find out by calling the State Dept (+202-663-1225) and find out that her visa had been issued before her passport arrived the following day! That was nice....
A Couple of other bits and pieces:
5. We got a reasonably good ticket price for her to fly out to the US within 10 days of getting the visa by going to http://www.mobissimo.com, which is a meta search engine for flights. Highly recommended.
6. Her visa had the following on it: "Upon endorsement serves as a temporary I-551 evidencing permanent residence for 1 year;" from appearances, it looks like this is standard.
7. POE in Newark was without problem.
8. Embraces and family hugs upon arrival were celebrated by all 3 of us!!
Hope this is helpful to somebody[ies]. The upshot is: 1. Make sure you have all of your original documents in, 2. Don't get discouraged by clerks and VFS staff, and 3. Be persistent, and 4. Don't bring anything to VFS, unless you have someone with you who can wait outside with your stuff.
Matt & Chandra
So happy it finally worked out though you guys were put through a lot of hassle! 
Not bad after 14 years of marriage! 
)