Translation - Italian-English - Con te partirò

I think "I'll leave with you" fits better. It may also be useful to note that when sung in english it is changed in "time to say goodbye".

I'd choose "I will leave with you".

well, "partire" can be translated in many ways. "leave" and "go away" are rather the same, imo.

Same difference between "partire" and "andare via", it's purely a matter of style.