Hi !
For Instagram, it could be possible but I still need to figure out how I will do it exactly - but there's no technical impossibility - (as "data fetching" is very different depending on the source), but I will try to implement it as fast as I can.
For the "tag dumping" on Instagram, yes it works. It will trigger the cross-post but only for the top "Insta", so if there isn't any hashtag in it, you won't have any Steem tags (except the share2steem one).
Thanks for the reply! And ok good to know, will definitely be giving the instagram tag thing a test in the near future