I never really expected much friction, honestly.
Starfleet Officers & the Maquis were both still Federation citizens.
Not to the Maquis. Maybe on paper, but they felt betrayed by the Federation, their homes given up to the Cardassians as if it was nothing. I doubt these people would just say 'yeah, let's all be happy people and hold hands'.
Sure they would co-operate, because of survival, something IMO Maquis are better at then Starfleet officers.
I'm not sure how many VOY fans watch DS9 and the birth of the Maquis, since VOY really didn't pay enough attention to the entire Maquis backstory. There is enough bad blood between both parties for them to work together just like that so quickly.
IMO, they really should've spend an episode or two in the beginning of season two dealing with these tensions.