I've gotten a couple of these in the past. This is a fake mail and obvious phishing attempt. At the bottom of the message it clearly states,
Note: This message was sent by another player. It was not sent by the Guild Wars 2 Team.
ANet puts that disclaimer on all in-game mails sent by other players to ensure that you know that it doesn't come from ANet or Guild Wars.
The right thing to do is report this to ANet - I think they have a special thread just for these types of fake mails. They can investigate and ban this En Merica player's account . Do not under any circumstances go to the "recovery" site listed in this mail. That's completely bogus and will likely try to steal your login info, or even install malware on your computer.
For GW2, there isn't much difference between windows 8.1 vs windows 7. I've got a laptop with 8.1 and two other desktops with 7, and GW2 seems to run about equally well on each. Since Windows 10 is coming out soon and will be a free upgrade from either, it probably doesn't matter either, so I would recommend going with whichever option is cheaper if you have a choice.
Other things to consider:
Pro's for 8.1: Seems to boot slightly faster and it offers support for touchscreens.
Pros for 7: Interface seems easier to use / more intuitive, especially if you've gotten familiar with previous versions of windows.
I fear that all those people clinging to the hope that HoT will release in the Q3 2015 timeframe (July/Aug/Sept) will be sadly disappointed. If it does release in 2015 at all, mid-to-late Q4 seems more likely.
In order to obtain ectoplasms, the rare (or exotic) item must be level 68 gear or higher. The rare items that can be purchased using Ascalonian Tears are only level 30 and ones purchased using Deadly Blooms are only level 55. This is not a change.
If you're looking to run dungeons for tokens to buy rare gear to salvage for ectos, consider Citadel of Flames (level 70 gear). With the lower level dungeons, you can save up more tokens and buy higher level exotics instead.
Beyond this, dungeon tokens are also used by players to unlock dungeon specific armor and weapon skins, and it takes many to unlock all the skins for a single dungeon. The tokens are also used to buy Gifts needed for crafting certain legendary weapons.