I believe there are several mods such as Malrubius' GAFH that add quite a number of triggers without any loss of performance. I don't think you'd notice any difference from splitting those triggers out.

As for show_me scripts, the AI can't "use" them - in that it can't activate them. But this is a matter of the mentality of the player, if you want to put a bunch of stuff into a script that's integral to the game then it would be cheating for the player not to click on it. And modders will never be able to prevent a player from cheating if he wants to. And there's nothing to stop you having a blank "click on this" piece of advice so that the player doesn't know what change will happen.

But no, if you want to be sure to be able to help the AI then you'll want to use a show_me background script and not a show_me event script.