Are there any victory conditions besides blow up the opponent?

IF you play a mission then yes. The victory conditions are part of the mission description. There are missions in the core set and all the box expansions (not the blister pack plastic ones).

In tournament play there is normally a time limit, victory is determined by who destroys more points of the opponent's ships.

So it is either a mission with defined ships or who destroys the most?

No scenarios where you choose your own group of ships?

And thanks for defining this from tournament play...I meant to ask for that in the original post.

The missions may or may not have defined squads. Most have some restrictions on choice of squad composition, but don't fully specify the squad to use.