Hi, please share your cp3 file or screenshot.
Explosion positioning issue:
I think your layers are set to different parallax? Spawning an explosion on asteroid should place it right on it. Make sure your origin is consistent as well.
Lasers not showing:
Sounds like you're drawing lazers as a straight line that touches the asteroid rather than travelling? If your laser is touching and being destroyed the same time it touches the asteroid, you won't be able to see it. There are several ways to solve this, but animating the laser and destroying on last frame. You can delay when it gets destroyed.