by amachno
Q1: you can play vanilla pandemic using the legacy one (only before playing the campaign). I would definitely recommend to play few times in order to put everyone on similar level.Q2: I think it is ok to play solo, pobably controlling 2 characters. This is definitely managable, some even suggest controlling 2 characters each in 2 player games.
Btw. you don't need to play each scenario in the same player count.