1a and 1b. There's no doubt that Wlad had a superior resume, faced the better opposition and sought unification fights, but you can't help but wonder without big brother retiring whether he would ever have made it at all. And when big brother did return, would Wlad have been a shoe in to take home the green belt, not in my book. Wlad was greater, by almost any measure, but Vitali was always seen as better.
Not most. Some thought that (me included, if you mean h2h) for some of the period. Wlad's domination lasted from April 2006 till Nov 2015, 113 months. Vitali was only active for 47 of those months. And others (including Vitali) might argue that Wlad was better throughout the period.