Interview waiver (Dropbox) for dependents

Dear Members,

I have my H1B petition approved and my next step is to appear for an interview. I hold B1/B2 visa and do qualify for the dropbox program. I have the following questions.

1- My spouse and kids (all under 13 years old) have no previous US visa. Do they also qualify for the interview waiver and can I apply for their visa with me using dropbox?
2- In case they have to apply separately after my visa is approved then can I accompany them in the interview or they will have to go to the embassy without me?

Your advice in this regard is much appreciated.