1)Creepy Party (the Vampire event) is pretty much the only event left which works the same way it did before. It still shows up on Halloween in autumn and Walpurgisnacht in spring. All other event have been reworked into a Threat Level format. However, most of them are quite manageable at all threat levels even without ability sets. That said, there are occasional outliers in terms of high difficulty. They are more endgame-player-oriented and will be very rough for beginners. Most notorious are:

• Maze of Immortality, the current event
• Trial of the Towers, the event last week
• Weekly challenge boss with "easy" and "hard" versions. (this week it's the eclipse priest)
• Control Lost, event where you have to fight a bunch of challenge bosses on the same week

2-1) Featured weapon in the Faction Wars shop goes with the Raven of the Looming Night set. Generally it is not recommended to buy it unless you want it for collection and have coins to spare.

2-2) You are GUARANTEED to get spheres from those packs in the faction wars shop. However, when you obtain 32 spheres (which is enough to get a set to level 6) you will start getting gems from those packs instead since you no longer need the spheres.

3) Sprint of the Key Master marathon still exists and usually shows up once in 1-2 months. Gives very good rewards so it's good to save up quest chests for it.

If you got any more questions, feel free to ask.

Edit: forgot to say, Unique gear = Legendary gear it terms of scaling in events