Yes, you get it shortly after defeating the 5th gym... It's a long-but-well-worth-it wait!
Yes, it can.
Teach it to a Pokemon, enter the Pokemon screen, chose the Pokemon that knows fly and select where you want to fly to.
After you finish Driftveil Gym and you're going to exit to Route 6, Bianca will appear and want a rival battle. After you defeat her, she will give you HM02 Fly as a gift ad prize. This is for both Pokemon Black and Pokemon White. I hope this helps!
No.
You'll need both Tornadus (Pokemon Black) and Thundurus. Have them in your Party and go to Abundant Shrine and Landorus will fly down to encounter you.
It was no more than 3 minutes and you get to watch a legendary fly during it.
After you beat the 5th Gym Leader Bianca will challenge you West from the Gym. If you win (or lose), she'll give you the HM Fly!
Teach a Pokemon Fly, select Fly from the party screen, and select your destination. You get Fly after you defeat Bianca in Driftveil City.
reshiram thunderus tornadus landours
I'm inferring you meant Landorus. You'll need Tornadus from the Pokemon Black version and Thundurus that you would have in Pokemon White, then take them to Abundant Shrine and interact with the shrine. Landorus will fly down to encounter you.
u defeat the driftveil gym and then go to then head for route 6 battle bianca and then she gives u HM 2 fly
HM01 Cut HM02 Fly HM03 Surf HM04 Strength HM05 Waterfall HM06 Dive