I have read that they charge extra above the all you can eat price if you do not eat everything. Is this true and how much more can it add up to? How big are the trays you have to order for AYCE?

Portions are not very big.

Yes its true, but they if you left like a entire roll. Its not that they gonna charge you for each piece. You can ask but they do that so people dont be exaggerated ordering rolls that they are not gonna eat or ordering more what they are going to consume to left something to go. I recommend go in a large group or with people that you know that eat much so you take advantage of it.