My spouse got her H1B visa stamped last week, currently in india. I am working in canada on work permit. I have valid B1/B2 visa. Can apply for H4 visa from Canada, if yes, is it going to be a dropbox / interview ? or Can I travel on B1/B2 and get converted to H4 after landing in USA.
Yes you can and most probably you may qualify for dropbox.
Yes, you may travel on B2 and apply for a change of status in the US. It is highly recommended to apply for such a change of status after 90 days of entry on B2.