1) I think that is quite likely. Alekhine was a great player, but I believe his victory over Capa had more to do with psychological factors and Capa's lack of preparation than superior ability. Capa, unfortunately, had some bad, lazy habits and was accustomed to just coasting - as that was all he had to do against most opponents. When Alekhine really showed himself to be an opponent on a level beyond any Capa had faced before, I think Capa paniced and lost confidence. I think something similar to this happened to him in the St. Petersburg 1914 tournament when he played relatively badly in the tournament final after his famous loss to Lasker only to take his game to a higher level afterwards.
2) It's possible but unlikely. Larsen was a strong player, but he just was not as tough a match player as a tournament player. I think the odds would have been against him making it through two more Soviet GMs to face Spassky and then beat him.
1) Anyone think Capablanca would have regained the World Title from Alekhine had he been granted a rematch by the latter? Would he have been better prepared this time round?
2) If Robert Fischer had never existed, does anyone think Larsen could have got past Taimanov, Petrosjan and whoever else he would have to face instead of Fischer, to play Spassky for the World Title in 1972? Could he have beaten Spassky?
Would like to hear anyone's opinions.