Can followers of the active character pick up Mission/Campaign chits?
I believe the answer is no. The rule on picking up Mission/Campaign chits is:
7.2.4 Picking Up Mission and Campaign Chits: Each time a
character starts a phase of his turn, he can take any mission and
campaign chits that are in his clearing, subject to the rules
governing each chit. He puts it with his active belongings. Hired
leaders and controlled monsters cannot take these chits.
A following character doesn't actually have a turn, so he can't pick up a Mission/Campaign chit at the start of phase of his turn:
7.11.1 The Follow activity is a special activity that the characters
can use to move as a group. It does not have a separate function
of its own -- it is used to do other activities. One character, native
leader, or controlled monster (the "guide") records his turn
normally, and the other characters or hired or controlled
denizens (the "followers") use the Follow activity to share in his
activities as he does them. (Also see Rule 6.2.7)
Note that the followers "share in [the guides] activities as he does them." Only the guide records his turn normally and does activities. The followers only share in the activities -- and only in certain specified activities.