As for #2, i do not think there is any evidence to support the claim that the Knight would have any significant advantadge in a confined space, nor is their any evidence to suggest the Samurai would either.
A Chinese Win Chung martial artist in a confined space would kick either of their asses.
As for #3, the Samurais style would be to parry with his sword, as would the knights(though a knight could also have a shield). A tai chi swordsman on the other hand would definitely attempt to evade his opponents strikes entirely.