How long has this "internet money laundering" scam been going on?

Just today I got an email from some mr.Masagambe or whatever from the West African Development Bank, which apparently has upped the ante to $1.5m. I’m sure you’ve all received some e-mail like that. The details and names change, but it’s always some obscure account in Africa, and you have to give them your details so they will transfer a huge amount of illegal money to you and get a cut. I remember when I first got that email, and it was before 1998 (I still had the old email address). Could have been even before 1996.

So here are some questions:
1) Are they so successful that they’re still running the same scam for over 10 years? I mean the internet has been around long enough for people to have their eyes open, right? Or are there still enough idiots in the world to feed these guys?
2) How exactly does it work? I mean, even if I answer the guy, apparently I give him a bank account and he adds money to it. Obviously he wouldn’t add anything, but just by giving him my bank account number, would he be able to steal the money that way? Or do people also provide PINs etc?
3) Let’s say that the deal was for real. Really real. No internet scam, no risk, nothing. Morally speaking, would you do it? The money offered is usually some inheritance that hasn’t been claimed, or stolen government funds and then the president got arrested, or some dodgy stuff like that. Would you take it?