Feral druid is odd because it's the only tanking class where it's frequently ideal to mix some PvP gear in for tanking gear. The reason is because clefthoof is the only druid tanking gear that actually has any defense on it. While defense is preferable to resiliance to hitting the uncritable cap, it's not always possible to do it with current itemization without resorting to the heavy clefthoof set.
Don't get me wrong, heavy clefthoof is an excellent start, but eventually you will want to upgrade. PvP gear is a great substitute when you don't have enough defence because resiliance is so cheap and PvP gear is built towards survivability. Look at getting the vindicator's dragonhide peices first; belt, bracers, and boots. They are easy to get and for any fresh 70 druid will be excellent for both tanking and dps.
After that though, I'd recommend you look at traditional PvE peices for a tanking set. You can use S1 dragonhide for tanking, but it offers less mitigation then blue peices for the same slot. Remember that as a druid tank your primary stat is not stamina, it's armor.
Dps on the other hand can benifit alot more from PvP gear. PvP rings, necks, backs and weapons are all great for PvE dps being on par or better then anything you'll get out of Kara. If you want to get into arenas the S3 gear is also great for dps.