H4 Visa stamping dropbox questions

[Joe03]

I'm on H1B and my wife is on H4 visa.She is eligible for H4 Visa stamping dropbox and have below questions:

Step 1. Print one copy of the Drop Box Confirmation Letter.
Step 2. Drop off your listed documents at one of our 11 Document Drop-Off locations.
         Current passport and any old passports with a U.S. visa.
         One photograph (per U.S. visa specification).
         Photocopy of Principal Applicant's Form I-797.
         Photocopy of Principal Applicant's previous or valid H-1B visa.

 

Questions:

1) Where I can see Drop Box Confirmation Letter after booking the Visa slot ?

2) Photocopy of Principal Applicant's previous or valid H-1B visa?

Please advise.