Well, the mentor-student relationship sounds fine for me. As for minigames, it would be a nice touch. If IS happens to make a survey and minigames take a great influence in it take for sure they will add it to see if results were accurate and it works out fine, but only if there are enough good responses to minigames (or anyother feauter they may think of).
Seconding this. Abuse I find it as a useful trick newcomers or beginners have to get through the game challenges, as well as starting to know how to play, make strategies, see which units are better above which, etc. I used this when I started playing FE, I tried to see which units gave good resutls, which strategies played well for the units I train, then started increasing the difficulty to see if what I have learned was good enough. Abusin RNG, arena, tower/ruins, all of this is just another way to play, you're not forced to do so, so its up to the player to choose if use it or not.
In a side not, I would like to see a training option for your units (kind of what FE3 DS has) but with your own units. For example, pitting Ike against Boyd while in base. This to earn weapon exp and just a bit exp. Obviously, limiting the number of times a unit can spar while in base to avoid it being used too frequently.