So...i can't look up or down with mouse? I need page up or down to do this? Seems weird. With mouse control I can only look side to side. Am I missing something?

Press U in game. It is the default key to turn on the mouse aiming.

In the old days you didn't need to aim up or down... or even straight xD If the enemy is in front of you, the bullets, missiles, etc... will hit it (in the case of missiles you can actually confirm this since they go up or down to the enemies).