As far as the fondant goes- I disagree about fondant being only decorative...there are many different kinds of fondant out there and while not everyone eats it, the cake decorator operates on the assumption that it will be eaten...i.e. it's fully intended to be eaten. When you consider that store bought fondant ranges from $6-15 per lb for some of the favorite brands- you wouldn't invest that much in it if it weren't meant to be consumed.
Most people who don't like it have had one of the brands with waxy flavoring, bad mouth feel, and/or it was rolled too thickly. It's unfortunate b/c the really good brands and recipes of fondant are amazing. The Disney fondant is actually pretty good- sweet, non-waxy, no mouth feel issues, and rolled to a proper thickness. I just say this b/c as a person who does cakes on the side, I get a lot of people who try my fondant and are shocked that they actually like it since they normally don't...and the Disney fondant is fairly similar consistency to my homemade fondant.
If you're still not sold on fondant, they should be able to do something with a crusting buttercream that comes out with a super smooth appearance.
As for the design, I know some of the bakeries will help you with your design. While I had very clear cut designs when I've ordered cakes, I've seen people do a bit of back and forth w/Chef Brian at the Contemporary to find tune design concepts. I think just get the ball rolling and see how it progresses.