The term Anti-Virtue usually refers to the original dungeons that oppose the virtues... Covetous, Deceit, Despise, Destard, Hythloth. Shame, and Wrong. Currently, anything you kill in those dungeons gives you a chance at an artifact drop. Some of them are nice in themselves, but they are also good with the current trade-in "Spring Cleaning" program.
For more information on the "Spring Cleaning" program, I'd check the Publish Notes for Publish 52 through to 54. A lot of the "New Items" you asked about come from this program.
Publish 52
Publish 53
Publish 54 (should publish this week!)
The main event series has been slowly moving forward for 18 months or more so it would take a better historian than I to bring you all the way up to date.
In Summary, the story line is leading up to the opening of the Stygian Abyss Dungeon (expansion pack). So far, it has resulted in several invasions (Ophidian, Magincia, Vanguard), the destruction of Haven and Magincia, the opening of the rift in Moonglow, the appearance of the shadow lords, the discovery of the "Book of Truth", the relighting of the "Candle of Love", and we still need the "Bell of Courage". Those three items are needed to open the Stygian Abyss.
The current event is "the 6 Mysterious Strangers" that are spawning in areas throughout the world (seems stuck in Hythloth though). These are like the champ from a champ spawn in toughness and when they are killed, they drop (on the ground for all to grab) gold, special gems, and even artifacts.
I have not changed my main template (OK, I stoned some skills off and on for special purposes, but always returned to mage ASAP!) or suit since right after ML was released, but I am PVM based and whether or not you need to update will depend on the fighting style (PVM, PVP, etc.) and what template you use.
and lastly.... Yes, the new "Greater Dragons" can be soloed... even a paragon version... with the right template/equipment.
Hope that all helps and look forward to seeing you in game some time.
Safe Journeys!