Featherfoot is one of the cross-class skills you'll almost always have in your selection as a WAR. Second Wind is also good, but gets swapped out depending on your healers and/or what else you need at the time. Both are definitely worthwhile.

Keen Flurry's not such a big deal. You can't use it as a WAR, so you'd only get use out of it for 9 more levels. If you want to level LNC anyway, feel free, but I wouldn't make a special effort for it. Edit: And yeah, for that matter, spend that energy going 6 more levels on GLA for Provoke instead.