Probably easy enough to find out by asking them. Though I think when it comes to R' Simcha Werner, one could be safe to make such an assumption (does he even go to any of these?).
Yes he goes. No, they don't eat the food.
I'd love to understand that. They're hosting a program and allegedly serving food to hundreds of yidden on pesach that they would not allow at their own table?
Mashgichim is different, but hosts?
They probably wouldn't eat in
anyone's private home, which is a widely observed custom in Lubavitch. As much as they are "hosts" - they are not running the kitchen according to their personal standards.
My in laws don't eat avocados - not just on matza, they don't eat avocados at all. At my home, we smear avocado on matza. My father doesn't have sugar, even boiled. My father in law does.