Re: Gun Ship MK1 | Documented so you can learn how to do it!
This is an excellent post. A good idea and a good example of how to do it, along with details on how to do it.
So, since you asked for advice, I will give it.
Your code seems a little inefficient. Your update code is running every frame, which is unnecessary. Only check actors, create rockets, etc when the F key is pressed AND when the timer has reset. It's unnecessary to scan for a new target when you still have a valid target, as well. Just check to see if your current target is valid each frame. You are also running a for loop over every actor twice each frame, which you really do not need. You can get away with running that code once.
I've attached suggested optimizations to the code with new comments on the optimizations for anyone to look at.
Whoever wants to look at this should understand the first piece of code first.
I'm sure there are even further optimizations that could be performed on the code, but that's the nature of programming.