It doesn't really matter, but some of the things does bleed on over from the first games to the second. However, it's not like you won't understand the things going on in the gameplay of B/W2 if you don't play B/W first.
I have Pokemon White so I'm going to get Pokemon Black 2 and also the black 2 version has Zekrom which I prefer to Reshiram. However this is totally up to you ;)
The differnce is that pokemon black 2 has a black kyurem and pokemon white 2 has a black kyurem and there might be more i do not know though.
YES, otherwise your wont understand pokemon2*
If you want strength than white cool Pokemon than black
no what are you talking about
The literal games that came before Pokemon Black and Pokemon White was Pokemon HeartGold and Pokemon SoulSilver. However, the newest Pokemon game to introduce new elements, areas, and Pokemon was Pokemon Diamond and Pearl.
Tepig
If you mean battling one another then yes
Ghetsis should be in front of Black City for Pokemon Black.
you should get Pokemon white and choose TEPIG AS your starter.
If you Poke Transfer from Heart Gold to Black, the Pokemon should be in your box
You should have Zekrom already by that point. If you're playing Pokemon Black, then remember that Zekrom is N's pokemon, so you won't be able to get it. You need to trade it from Pokemon White.
Before Black City and after Marvelous Bridge.
Haunter