We've walked in to Chef Mickey's before, but it was very early and it was Summer (when fewer people eat early). I think we were rather lucky since they had a special early seating for a large group of kids.
As I recall, they had us wait a few minutes after 5 to get an idea of how many 5:00 no-shows they would have, then we were seated. If everyone had showed, we would have had to wait for the next block and of course any other walk-ins ahead of us.
At least a couple (possibly most) restaurants give you the little hand held light/beeper things. But I doubt they have much range.
Don't know about the carry-out.
I will be going to Disney for our first trip in May w/DH,DD-7, DD-5. We are staying at the CR. I made ADR for Cal Grill so that we could definitely watch the fireworks from our table one night. Our family is very laid back and we don't like to be on a rigid time table. If we don't make ADRs for Chef Mickeys or Concourse for the first week of May, do you think we could still get seated for an early dinner? If you are on standby, do they give you a beeper? If so, would the beeper reach our resort room so we could go back and relax in our room while waiting on a table to open? Do Chef Mickeys, Concourse, or Cal Grill offer carry-out? Please help a newbie 
