Vertical Shooter tutorial questions

Ive been working on a a game for a client for a few weeks now, after realizing the projct might have been a bit ambitious for my coding level, i have turned to various online resources to help me get through this. Suprisingly, so far the vertical shooter tutorial found here has been the most help.

As for right now, the problems i am having are my collision detection. The diffrence between my project and the tutorial, i am shooting many bullets, machine-gun-style.

Another problem i seem to be having is the created Mc’s that represent my enemys fly for only a few seconds and dissapear, understand they are set to do so after reaching <0, however this happens 75% to the right of my stage!

Heres how i have attempted to work the collision, it works 1/2 of the time, the other- none at all!

if (this.hitTest(eval("_root.bullet"+bulletNum)))

Any help would be appreciated, thank you so much.