1: On the train. At the mall. In restaurants (Denny's is one of our frequent Hunting grounds). In the waiting room at the doctor's office. I suppose that's the extent of it, I wouldn't play my 3DS while walking around. Probably.
2: Fuck no. Though of course I keep the volume low or off if i don't have headphones, I'm not trying to be obnoxious.
One time at Applebee's my waitress asked me what I was playing and started talking about WOW or something. Last time I was at the doctor's, I was sitting next to a man much older than me playing what looked like an RPG on his DS, his son next to him playing a 3DS. Video games are not stigmatized the way you seem to think. Lots of people play games on all kinds of devices. There's absolutely no reason to be ashamed to be playing a 3DS.
Maybe some closed-minded people will look down on you. These people will always exist and they will find reasons to look down on you no matter what you are doing, whether it's the clothes you're wearing, or your accent, or the color of your skin. Ignore these people.
