ActiveXObject in Firefox or Chrome (not IE!)
ActiveX is only supported by IE - the other browsers use a plugin architecture called NPAPI. However, there's a cross-browser plugin framework called Firebreath that you might find useful.
No for the moment.
I doubt it will be possible for the future for ActiveX support will be discontinued in near future (as MS stated).
Look here about HTML Object tag, but not anything will be accepted. You should try.