Fat chance that the Red Proto-Drake will be gone any time soon since it's only a 280% flight speed mount. Still, anyone after the Red or Blue Dragonhawk mount (when Blizzard gets off their backsides and increases its speed to 310% instead of a measly 280%) from Mountain O' Mounts should count the Red Proto-Drake among the 100 that they'll need. Or you can just look a lot cooler riding on a big red proto-drake instead of a puny red or blue bird that looks like it would snap in half if a Tauren sat on it.

The achievements from the heroic five-man dungeons aren't as difficult as they used to be pre-Ulduar, but a lot of them are still a pain in the backside. They're all listed here per dungeon, all rated for their difficulty with the appropriate tactics and under the assumption that the groups trying for this are decked out in Naxx 25, Ulduar 10/25, or ToC 10/25 gear.