Feral Dire bear will be a great off tank for packs and adds. The sheer amount of threat generated with the growls and swipes will help the tanks focus on the boss.
The Cat form will not really be very usefull as you are nothing like a rogue, the bleeding closing move might not have space on the target's list.
In both forms, leader of the pack might be viewed as a must have by your Raid Leader. As well as fairy fire (feral)
As a healer, you will not be able to heal the main tank since your healing touch will deplete your mana like there is no tomorrow. Your role, if done properly and used wisely by your Raid Leader, will be to keep the raid alive with your HoT and Tranq. It is illadvised to use healing touch unless it is to save from a wipe.
A druid is a valuable part of raid group. But you have to mind yourself and get ready to get busy cause you will NEVER be able sit back and focus on a single target. Not as a tank, nor as a healer.
PvP wise, well geared and warmed up. You will be a wall. Keeping the BG alive or running the flag.
I hope my humble experience as a druid helps you.