Whoa, thats a lot of help there. If I were you, I would go through those one at a time, looking for posts regarding each issue.
I will try to help you with some of that code though. Duplicating enemies is pretty easy. Make a movieClip that is supposed to be the enemy. Say an evil frog. Place that frog on the stage. Then use the duplicateMovieClip() function to make copies of this evil frog.
I use a for loop to create these extra movieClips.
You can use if/else statements to remove these movie clips once they get to the edge of the stage, stuff like that to make it more interesting. Hope that helps.
/* i hope you know for loops */
/* also, the "evilFrog"+i, creates the new name for each instance created by the duplicateMovieClip code, and the "i" adds it to the a higher level on the stage. */