1) Vergil, although i like Dante's hairstyle in DMC4, in DMC3 it's too... teenager, i'm a grown ass man but i would easily use the "Vergil hairstyle" if my hair were not too thin and actually could be sustained by any kind of hairgel in that shape, even when it's not too long it tends to get down unless i use such an ammount of hairgel that the hair feels like a brick.
2) Difficult one. Considering DMC3 incarnations, i would choose Vergil, but DMC incarnation of Dante is badass even if not in the Ryu Hayabusa level. I think that Dante itself is even more badass than Nelo Angelo (Vergil) in DMC, he's ironic but still has that menacing flair. Nelo Angelo look like a tough warrior, but not exactly someone i would fear to look in the eyes if i had to fight; even considering his demonic look, haha
3)They seem to be equal in power, their natural abilities must be equal seem that they're twins. Purely talking about swordfight, i think that Vergil has the upper hand; but in general combat abilities, Dante has more options and is not only focused on "hand-to-hand" or "sword-to-sword" fight. Vergil is more focused and dedicated but he is narrow minded (i respect it, but he imposes a limitation to himself). But i still pick Vergil to this one, i think that these people who have a warrior mindset tend to be focused and for the most time they can win their battles; Dante was only able to really win when he had a MOTIVATION (joke intended) for this, Vergil's motivations are fighting (Dante likes this too, but as way to have fun more than a way for improvement), improving and power itself.