Nice script, just a suggestion: add a _ before the bomb (_bomb instead of bomb) variables in the script, this change the variables from global to local thus avoing possible conflict with other variables and saving OFP memory resources.
The sample mission it's ok, but you've to change the name of the script fired by the trigger from [plane,10] exec "a10bomber.sqs" to [plane,10] exec "bomber.sqs" or you will receive an error message once the plane enters the trigger's area and the script doesn't run.
Klavan