On the tablature, Should there be a 2 on the E string for the last note?
You can play that note, just make sure to play 2 on A as well.
Other than that, in general, if you see more that 1 note indicated (chord, partial chord) it should be plucked if there is no strum notation? pluck instead of strum becomes particularly important in the 13th bar
You can, but there’s no set in stone rule. Really up to you if you like the sound of pluck vs. strum.