Thing you would change?

[Wasp]

-Decide which unit a heir should be in.

I believe you can do that already, although a bit clumsy. Once a heir becomes 'unassigned' (when he becomes 16), he'll appear in the first unit built (the following turn, of course). You'll just have to micromanage it a bit, but it works.

Or do you mean something in place of this?

For the rest, excellent points regarding singleplayer. I haven't played multiplayer, so I can't comment on those properly, but those look very logically too.