I think adding those actions would be great to have in Feralheart, I personally think IT servers have more to offer than Feralheart. It would be good to add some of IT's features like those actions.
It wouldn't cause lag, "truckloads of money", remodeling models though, it's all in a matter of experience, patience, coding and skill. I would imagine Feralheart was coded and made similar to how IT servers are compiled. Kovu most likely has these original source files/codes on his computer. He could actually use the armatures and skeletons from IT and add them to Feralheart models, it's possible to swap animations and models but it would also require a change or edit in certain files.
So yes, it's possible in a way but it's most likely not going to be added anytime soon. Hunting is planned to be the next update for Feralheart.