You're right there are quite a few chocolate desserts at the 3D. The offerings will change from week to week. I know the one we attended late in October had a pretty good variety of non-chocolate/no nut desserts, such as, pumpkin cheese cake, varied fruits, sugar cookies, flambees, fresh donuts (so yummy). They also had tables of savory items such as prosciutto and Figs, melons, cheeses, etc.
There is no seating for Illuminations. The standing area is right at the entrance to World Showcase, between the two merchandise stores. Great view and last year we received 3D glasses for viewing.