Ok you have stated that this is an important (solo style) confrontation, that the Queen is supposed to be a serious threat, and that she will have many allies. You have alos stated that she will be used against a level 16 party.
Here are my initial thoughts on the creature.
HPs and Stats:
From the creatures stats I would have expected:
HPs: 336
Fortitude: 27; Reflex: 30; Will: 31
The HPs is a special case because she is doing something unusual when dead, i.e. comming back but I will cover that later.
Her Will defence seems a little high, even with MMI creation I would have had her at 33 max, in this case I think that 32 is probably high enough.
The +5 to saves vs. charm is in keeping with her race, so that is a nice touch.
Anima of Peace
I have done something similar in the past, but not quite to your extreme. This is a really strong power and one that your players might not like as there is nothing they can really do about it (especially melee characters). Personally I would change it so that any enemy starting their turn inside the zone must make a save, on fail they cannot make an attack that includes the Queen until the start of their next turn. This would still allow them to attack other creatures, and would mean that they could still move in and attack which encourages tactical movement.
The way you have the power at the moment is pretty much the equivalent of a stun, and might not be fun in actual play.
Longsword
Nothing wrong there.
Fey Missiles
This is probably the Queen default attack, and is spread out. I think I would increase the damage to 2d8+7 because she cannot use this to focus fire.
Thunderwave
Nothing wrong there I suppose. I might be tempted to make this a recharge 5,6 power, increase it to blast 5 and increase the damage to 2d10+7.
General note - all her at will attacks doing the same damage is a little dull, but I don't think anyone would really notice this during play.
Dominating Gaze
Well a close blast 5 dominate is a powerful effect. If this was a solo creature with no back-up I would think it was a perfectly acceptable power. But as you have said that there will be other creatures in the encounter this could case some problems.
Having said that, it might not, its a tough call to make without knowing your group and the other creatures in the encounter.
Having it recharge when bloodied is also adding to its power, but if you feel it is OK the first time it is probably OK the second time.
If I was going to change this power I would make it a single target attack, with a recharge of 5,6. It would still be powerful, as it could be used several time during the encounter, I would also keep the on bloodied recharge.
Fey Step
This is a powerful Fey creature, remove this power and give her a teleport speed of 5.
Bloodied Surge
Fair enough.
Death Curse
This is where you might have gone slightly mad.
Going back to HPs - I would expect this creature to have 336 HPs (total)
You have 285 HPs, then on death rise again at bloodied level, but with insubstantial (which is effectively worth twice the HPs) so your creature has: 285 + (142 x2) = 569 HPs.
If this creature was a solo (MMII) I would expect about 672 HPs (total), so your creature is approach solo level HPs for elite value XP.
What I might do in this situation is change the HPs to
standard - 252 HPs (bloodied 126)
rise again - 60 HPs (insubstantial)
Banshee Shriek
I think that burst 10 is probably overkill, especialy because it is a zone. I think that burst 5 would be lot more reasonable.
However I think you should really have her rise as a different type of creature, as it keeps the encounter interesting. Having her rise as a brute or a skirmisher with a whole new power list would be a lot more exciting and fun.
Anyway these are my initial thoughts and opinions. I hope they help.