Thanks for thinking of me @dandays. I don't know if I'm an eSteem ace, but I have been using the app since it was first developed, so I've learned a couple of things along the way.
It is my understanding that when Steemit releases Smart Media Tokens our ESTM will be a SMT and will have tradeable value, just like Steem does.
Gift is pretty obvious. You can click on that and send ESTM to a friend. I use that when I pay out ESTM for awards for contests.

Sponsor is what you use to get your post pinned to a recurring spot on the eSteem feed. I just paid to sponsor my latest contest post.

And boost gets you a bigger eSteem vote.

Hope that helps! There is nothing wrong with stackin a few ESTM, either!