To answer the original question...
We've done the Crystal Palace twice before park opening on non-EMH days. One reservation was for 8:10 and another was for 8:30. In both cases we saw characters and enjoyed our food and were done before the rope-drop. For the 8:30 reservation we checked in early and were seated well before our 8:30 time, making it easy to still make it to the 'inner' rope drop.
As far as when you finish with your meal...
The last time we did this, you could freely walk around Main St. and the hub area as they were open, but the secondary ropes would keep you from going into the individual 'lands'. As for Fantasyland, there was a rope on the other side of the castle, just before the carousel. By the time 9am came, some people from CRT had also made their way to the rope, and there was a small crowd waiting for the drop. However, everyone seemed to go to different things, so it still felt very empty for a while. (Although this was before the whole Anna/Elsa M & G).
What was nice was that even though the front of the park had rope drop at the same time, it still took a while for those at the front to make their way back, so it was definitely worth it. In all, we felt like we had a good 30-45 minutes of an empty park, and then still another 2-3 hours of very low AM crowds and accomplished a LOT! Unless something has changed, I'd say those with early ADRs already there for the inner rope drop will have even more time now that the front entrance drop is now an orderly walk rather than a free-for-all run.
Even though I have not done this on EMH mornings, I'd assume the 'inner' ropes are down and after breakfast you'd be able to walk around the park, but maybe not get admitted onto the attractions...?
Good luck and hope this helps!