If you are attending the party, I would not spend time eating at a restaurant during the party time.
I would suggest eating before the party starts.
When we have done a party, we ate at 5 and had plenty of time to get everything done. We also don't do M&Gs.
If you plan to do M&Gs, figure out which one you want to do and how popular they are. The popular ones can have a line pushing 2 hours.