I like DmC's Dante personality as it is. And i don't want to see his personality change at all.
If his personality is changed like past DMC's, i'll shoot myself in the face!
The reason why i think his personality should stay the same is because its already been seen in DmC that Dante shows many sides to him and NT did a great job at making something non human....human.
Sure there could be some twist and things or have Dante having more inner struggles with himself, his decisions, his new powers and his lost brother, but i would like to see how DmC Dante goes on about it.
just a natural evolution of the character, nothing too dramatic
and for the second part of the question.
Maybe a clean shirt, maybe putting his hood on at least once in the ****ing game, and a hair cut.
I think the short white haired mohawk looked the best on him. (neoDante skin)