Hey for the first problem this the solution
you need to know that the exposition isn't looping is just created twice or more
When you put code like that : EnemyFighters --- Hull <= 0 the code start repeat himself until the enemy ship get destroyed
So the solution is to add ( --> ON event)
like this example a give you on the picture
For the rest of the problems I can't reproduce them
if you can give me the steps to reproduce them maybe i can help you more