H4 i797 and Dropbox Program

[h4wifelife]

I am planning to avail the DropBox Program when I go to India.

This is my second stamping. 

The first time I got it stamped , after marriage I did not have an i797.

After my g=husbands employer applied for his extension, I got an i797 too, petitioner being myself.

1)Can I still use the dropbox program, as earlier I didnt have an i797

2)Where do I specify my i797 receipt number

3)Should I place my i797 with the required documents