The two current events are kinda easy compared to, say, Halloween boss. As for ToR tickets, once you've cleaned out box three, I was done with it, which is just 3 ten pulls. The harpy is harder and has more things to buy, but even that one I'm almost done with.
As for characters, you really want 5* Ace characters, and for what you show, A2, N2, and Maria are top of their class type. You'll want the Neir weapons, from the weapon draw, and transmute the Wind Gun for Maria.