Hi. Do you eat meat?  I am vegan and don't eat or use anything made from animals
I do eat meat, but I completely respect vegans and vegetarians. I recently read that some vegans don't even keep pets because they view it as oppressive.
That's true - we say "ethical vegan" and are against the use of animals for anything! 
My brother in law is vegan for environmental reasons. Is that also being an ethical vegan?
Yes that's ethical because animal farming is bad for the environment and isn't considered  sustainable.  Good for your brother in law!
He's been a vegan for long time.  Eating vegan isn't all that difficult, really. But it was an adjustment at the holidays!
It is a hard diet to follow since it's no dairy or eggs but it's so worth it. Holidays are hard!
Restaurants seem to be a hurdle. There seems to always be hidden dairy, even when the waitstaff seems to understand what vegan means.
Yes!  And I'm Jewish and so much of Jewish food is varied including meat and eggs so that's even harder