Yes these are new and probably OP, I have hunters with over 200 XP running around. There are no XML tags for this feature so it needs to be python atm. In realty they should only be considered one or two promotions before you get your last promotion from combat with barbarian animals and units.
In my latest SVN game I noticed that hunters were staying in the AI cities leaving all the animals for me. This probably means I need to tweak the hunter line stats.
No, it means there is an AI bugbof some sort. The AI builds hunters explicitly and once built as a hunter a unit won't decide to go do something else und normal circumstances, so the implication is at they are not being built for that purpose at all for some reason.