Yes, if turkey is for sandwiches, I would look into the breast. Even if you have to bake it your self, it is still better part of meat for the sandwich. You can still cook ahead and slice it, but just make sure that it is say about room temp or a bit less when served. You don’t want it to be too cold.
Noodles. I think if you make with some sort of spaghetti sauce, then you can reheat in the oven. Boiling second time doesn’t make sense because it takes only 5-7 minutes to cook them completely, but boiling a lot of water takes time.
As far as lox goes, I was not concern about spoilage of cream cheese, I was trying to maintain at least a visibility of some adherence to kashrut, it is Bar Mitzvah after all. You do not want to give a wrong message to the kid, not on the day like that.
You are what you eat.