H4 visa stamping using IWP and dropbox

Hi,

I got h1b stamped in DEC 2015.
Till date never traveld to USA on stamped H1B.
My company filed LCA for h1b amendment and petetion got approved.
Should I restamped my visa using IWP and Dropbox?

Next question
My wife and 9 month old still haven’t got visa stamped H4.
Can I apply for h4 stamping for wife and kid using IWP and Dropbox?
Note:- my wife got valid B1 visa.

No need for another visa stamping as long as the previous visa stamp is still valid and has not expired.

The kid can avail IWP but the wife needs to appear in person as she has no previous H-4 visa stamp.