Please, to get more support write to me at firstname.lastname@example.org
Shortly: 1. This probably it's not depended on the add-on but on Firefox itselfves, maybe it's a but 2. Sorry, the "💎" emoji was missing and I've just added (you'll find that emoji in the next release!)
Takes very little memory; requires absolutely no permissions; provides the standard Unicode emoji set; works best when set to using Twitter Emojis (twemoji). Although, I am not able to pick non standard fonts I have installed like Mutant. One thing that doesn't require Unicode support, is old school emoticons. I would have really like a tab full of the most popular ones.