I've had good luck with search lately, but it does turn off when the traffic level is too high. Anyway, the last time this was asked was quite a while ago, so it's good to come up again.
Like the others said, there is an elevator up to the dining level.
Once you get to the dining level, there are 2 levels, sort of like tiers. The top one is at the same level as where the elevator lets you off. The other tier is down a step (or maybe 2). I think they set it up that way so that everyone can get a view of the whole castle area and the windows (even if on the top tier). Like Piper said, you might want to call back and let WDW dining know that you will have a wheelchair. Remind the hostess when you check in too.
And, the accessible bathroom has a key that you get from the hostess if you need it. The only other bathroom is halway up the stairs on a landing.