Rufus -
Your coaching style seems to be refreshing and a nice break from what typically happens in youth sports.
You know your players better than I do, but I have some coaching experience as well as catching experience, and now 4 seasons as an umpire ranging from 10 year olds to adult leagues.
Just remember, and I think you have a good grasp of this, that every moment can be a teaching tool. At some point F2 is going to have to learn to give signs, and it is going to get harder and harder to catch effectively if he doesn't know what pitch is coming. Then me, as the umpire, gets hit more, and then I get cranky
I would suggest involving your catcher in this someway. Also, effective pitching is repetition of everything, similar to a free throw. It might not be a bad habit to have your pitcher take a sign every time, even if it is going to be just fastballs that inning. This will help with repetition, and may avoid balks in the future when he gets older. Certainly will make him not have to think about one more thing, as it will become a habit.
These are my takes as somebody involved in youth baseball, not as an umpire or from a rules standpoint. But umpiring alot has allowed me to see lots of stuff, so I hope you find my advice somewhat worthwhile.
Like I said Coach, you know the situation better than any of us, so I'll let you be the final judge. Just remember, every moment something can be learned at the 11U level
Good luck!
(p.s. See, I can be nice to coaches
)