The Account Achievement Reward is a permanent addition to the game, there is no need to rush for points (since it was released we already saw the “leaked” rewards/the pattern go from 10k to 25k http://wiki.guildwars2.com/wiki/Achievement and yay for eventually being able to get all the skins).
As for the Zephyrites and the new zone do not have an official end date as of yet. It is presumed that the Zephyrites will stay through the next LS update, the election (how can you have a trade agreement with someone that isn’t present), and leave when that is over ~Aug 5th-6th. (That seems to be the trend for the LS updates, the first runs a month and an additional update 2 weeks later runs at the same time as the first and they end together). So if you want the Helm or Cather back skins it’s better to get them sooner rather than later.
As for the zone, that is still up to speculation if it will stay or not, the ship would be gone though. My vote is on a “no” right now, just because without the Zephyrites there would be no merchants or aspect crystals so there wouldn’t be much point to it still being open.
