I'm okay with GlimGlam being a Alicorn princess. It's not like an Alicorn Princess is special anymore. Plus GlimGlam's OP as all hell.
Who can say no to dat face.
Nope but eating out allows you to not have to cook, do the dishes, and buy groceries, so you're saving some inconvenience.
However, I love cooking. I make a badass scallop risotto and lobster spaghetti.
Well we clearly see her in the trailer (although that might be at the end of the movie when the ponies are celebrating. Usually movie trailers have the movie sequence out of order to throw off viewers).
I do like the explanation that she was defeated by Tempest Shadow (Even tho GlimGlam is OP as shizz), showing off how powerful the antagonists of the movie are.