I'm inclined to say no, purely because an ex was vegetarian and a little too pushy about it. It wouldn't put me off initially though if I really like a guy. Depends if he then tried to force his views on to me.
Yeah, it’s fine. As someone from a family with a vegan sister, I eat meat in front of her. Not disrespectfully, nor do I wave it in her face, but I’ll just quietly eat my chicken while she eats her tofu at the table. It’s fine.
Dating a vegan wouldn’t be an issue. Long as you’re respectful and so are they, neither of you have to forfeit your eating habits.