Uhhh dude a while ago
Chat with our AI personalities
Minecraft Alpha came out in 2009.
Minecraft had a 'soft launch' (started as an alpha/beta) some time around 2006, I believe
You need an a jar from alpha stages, which you can get with Minecraft Nostalgia.
You cannot in alpha
You can no longer do multiplayer in alpha. Minecraft has moved to Beta now, so there are no more alpha servers. Update the game, and then you can play multiplayer.