I also found out that RUSH uses click tracks and sequencers for their whole show (always have)
I forgot to comment on this. Yes indeed! In fact, a little trick I've seen them do is where they put a stop in a song. Wait (what appears to be) a totally random amount of time, and BAM!...all hit a note together WITHOUT even looking at each other! Then another break, and BAM! BAM! BAM!...all perfect with each other!
I was amazed at their timing! I couldn't believe it! A few years later I figured that out and started using some of that for bands I did some programming for. It allows you to be a little loser looking.
In fact, most people don't know that clicks can be variable speed if programmed to do so!
There is a lot you can do with them with a bit of creativity. And you are right, pyrotechnics, lighting, instrument effects, video, can all be synced perfectly...and in a way that would be nearly impossible or impossible to humanly do.
That doesn't mean it HAS to be rigid though!
Also, your mixer should work great. It would also allow him to control click, tracks and a stage mic (if needed) volume separately.
You may want to purchase some sound isolation headphones or earbuds if you don't own in ears for him to use.
Walmart has some Skull Candy ear buds that can do this to a point. I use them when mowing the lawn! They are only $10 but work pretty great for me.
Just make sure he has volumes low enough to not damage ears. The isolation of the headphones will help a lot with this.
Good luck!