1: I was freaked out by how he looked at first, because of his eyes, but I also thought it was unique. Once you see Illumi, you won't mistake him for anyone else, ever. Unlike say, in Fairy Tail, where Gray, Zeref, Rogue, and Mard Geer all kinda look similar.

2: No, there should be more art of him for sure. Or maybe I haven't looked hard enough.

3: Since Illumi's needles can transform his appearance, I think it's safe to assume that he has a few transformations he hasn't used yet, each with their own abilities.

4: No. If Illumi's character arc ends now and we don't see him again, then I will say it was a very unsatisfying end to his character. But I expect more from him in the future, just as I expect more from Hisoka.

5: I bet you Illumi will show up at some point in the Dark Continent arc. The way things are going, this is sure to be a long one. And I'm sure lots of characters we've seen before will get involved, like the Phantom Troupe.

6: My favorite moment with Illumi is when he's in his Gittarackur disguise and he takes the card out of the box before the 4th phase of the Hunter Exam. The jerky movements he makes and practically stabbing his hand into the box makes me crack up, it was so utterly weird.

7: I want Illumi to fight Hisoka, but I think it would be cool to see him fight Killua. However, Togashi tends to take the unexpected route, so I doubt that's going to happen. A clash between brothers seems too obvious.

8: I want to see more with his Gittarackur disguise, it's one of my favorite character designs in Hunter x Hunter. I wonder if he has special abilities?

9: I hadn't thought about this before. Honestly, there are so many characters to choose from in the cast, I wouldn't know where to begin when it comes to guessing which ones are under his control. My first guess, is possibly his own mother. His manipulation probably starts from within the Zoldyck household. Maybe he uses this to control his mother's feelings toward Killua? I dunno.

10: I think it's easy to see how he teamed up with Hisoka. As they say in an early episode, powerful characters with Nen abilities and potential can often determine the strength of one another and see each other with more respect. I think they must have met during one of Illumi's assassination missions, possibly with Hisoka unexpectedly helping out in some way or another.