I'm still wandering about on Routes 6 and 7, so no idea yet. However, my understanding is that it's done within the battle screen somehow. You might have to reach a certain point in the game to actually learn how to do it, however. After that, the option is available.
The one from Black 2, yes. Just have to move Braviary over and eventually clone it. Since my Join Avenue shopping is hampered by switching the game between systems, I have it in the 3DS ATM and can trade it to Black on the DS to clone, then trade it from there and possibly keep it in Black until I get the maingame completed (at which point I can breed in both games and can prep. breeding stations for different things in each game).