Welcome to the club!

I'll leave the pneumatic questions to others with experience in the topics.

To answer your other question, we use drills because they are easy to get a hold of, cheap and give an ideal speed output. They are tried and tested and we know they work. If you have another idea then by all means post a link and we can advise.

A flipper can be complex or simple. A lot of people start with a rammer as you get a good feel for the rules and experience your first event with a fairly simple machine. That's not to say that a more complex machine isn't possible. Just depends on your experience.