No, Cat DPS on it's own isn't a good reson to bring a feral druid. Raid Leaders bring a feral druid for one of 2 things; to OT, or to give a melee/Hunter group +5% crit.
As for your gear:
RED is your meta-friend. If you really want the extra 8% run speed, get a Cat's Grace (DPS boots) or Boar's Speed (Tanking boots) enchant.
Don't gem for AP... ever. For two reasons. First, the equivalent Str gem gives just as much AP, but is affected by Blessing of Kings. Str is worth 2.2 AP in some 5-mans, most 10-mans, and almost every 25-man. Second, Agi is better than strength for DPS at pretty much every realistic value for crit % and AP. There's a chart on the Druid wiki.
http://druid.wikispaces.com/ToskksDPSGearMethod On the same line, don't gem for crit rating. Agi gives almost the same % crit, and gives AP at the same time. If you need yellow gems for your meta (RED requires 2 of each), +4 Hit/+4 Agi. Only socket for crit if you're already hit-capped and need a yellow gem for your RED.
Start building seperate DPS and tanking sets. There are some pieces you can enchant/gem for both DPS and tanking without suffering too much, but most slots you have to choose between good DPS and good tanking. (Off hand, some things good for Cats and Bears are: +6 stats to chest, +15 agi to gloves, Agi gems, 2 Agi/Stam gems for RED)