Does it have a nunchuck included (one of these), as some of the games need one to play? I only have girls (but one of them is 7) and the Wii works best with active games (Wii Sports, Wii Sports Resort) - 5-yo DD2 can whup my ass at bowling and frisbee!
Yes, he can play against someone else, so an extra wheel is useful (not that DH and I wait till the DCs are in bed, and race each other, oh no) (and fall out when we lose, definitely not) (oh wait, that last one's just me )
Yes, we added an extra remote and 2 nunchucks, so the DDs could play against each other. They come with Motion Plus as standard now, I think (have scrutinised your link, and think that's a MotionPlus remote with it).
And not long afterwards, we also bought rechargeable batteries and a charger too though you can get a stand for charging the remotes