1. I haven't tried bikes yet, but I've heard mixed results. Karts 4 Life!
2. It's just as easy to get back to first, so I'm ambivalent, really.
3. MKDS... Maybe MKDD.
4. Medium--Neither here nor there.
5. I never really sat down and thought about it, but I think Tick-Tock Clock, Luigi's Mansion, and Waluigi Pinball would've been nice (for some reason, all that comes to mind is MKDS tracks... it had lots of good ones!).
6. Rainbow Road is, per usual, frustrating.
7. I've only tried the Wheel so far, so that's my favorite by default. Besides, I was so used to using a + Pad in MKDS that when I went back to play MKDD once, I was a mess--I figure the same thing might happen here.
8. Plenty of great new courses... either Coconut Mall or that one Maple Tree level.
9. Favorite Retro Cup? Whichever one has DK Pass, I believe.
10. Worst New: I can't think of any that are "bad", but there's plenty of bland ones. Daisy Circuit, perhaps? (how did she get associated with tropical things, anyway? If anything, it should be Middle-Eastern stuff...)
Worst Old: Pretty much anything from the original Mario Kart (though I'm pointing my finger mostly at that one Boo track).