Shooting walls/the ground/invuln enemies grants tick points. Missiles hitting ground and the back 2way give 20 per projectile hit.

Boss Timeout Info (From Boss Text Intro Vanishing to Death):
Roc Carrier: 2:08
Lunar Walker: 1:26
Cosmic Slime: 2:12
Constrictor: 1:16
Loki: 1:37
Big Bill: 1:00
Insane Ship: 1:02
Valkyrie: 1:41