Possibly, but most likely not. There closed beta was on September 6th. However, they might have one last beta test. Sign up for a BattleNet account and sign up for a beta account. Then you can see if they have any more beta tests for Diablo III.
Yes, Diablo is in Diablo 3.
No. There are Diablo 3 teaser videos on the Blizzard website.
Mephisto is mentioned, but does not appear 'in person' during Diablo 3.
Diablo 3 is out now, it was released on the 15th of May 2012.
Yes, of course people play Diablo 2: Lord of Destruction. And most people probably will until the release of Diablo 3. And even then, people probably might still play it from time to time.
You mean sites that sell in-game items? Most of them shut down with the release of Diablo 3 but I am sure there are still some out there. They are against the TOS however.
No, there is no pirate class in Diablo 3. If you mean to pirate the game, you cannot do that either.
diablo 1 is about 100mb diablo about 800mb and diablo 2 expansion another about 800mb
Yes!!!!!!!!! - but the beta just ended a while ago!
It's been over 13 years since Diablo 2 was a true Hype, so this would give you a perfect reason not to worry if Diablo 3 would be your 1st Diablo game experience.
Diablo 3 was released on May 15, 2012.
The requirements can be found at the official Diablo III website.