Nice!
Glyphicons are those included in Bootstrap and listed here.
If you want to add icons, you could make a OSGi bundle like the classic UI set (the proper way) - or the quick & dirty way, putting your image files in conf/html/whatever and referencing them with <img src="/static/whatever"/>.
Maybe I’ll add a few builtin iconsets like I did with the three already there though, if I come across one I like.