Bitcoins are released at a constant rate determined by the protocol. At the time, 50 Bitcoins were being generated for every block(this is now 25); and blocks are supposed to be found every 10 minutes. Miners compete amongst each other for this prize.
In 2009, you could mine using your computer's CPU and you were only competing with very few other people. There weren't large mining pools and dedicated hardware, so it was easy for anyone to run the client and mine hundreds or thousands of Bitcoins. It was so easy that you wouldn't think that losing your wallet was a big deal.
- Maybe, but it'd be a lot of work.
All transactions - including mined Bitcoins - are recorded in a publicly accessible global ledger. Many people download the entire transaction history on their own computer, and there are tools for working with it. It might be possible with some detective work to try to track down what address they were likely stored in using the clues given, but it's not easy.
- Nope - if you lose your wallet those Bitcoins are lost forever.
That's terrible for the person who owned them, but it doesn't impair the rest of the Bitcoin economy. It makes the value of the remaining Bitcoins go up to compensate.
There are already exchanges that will hold your wallet for you if you're worried about things like this. They're more secure than holding them on your personal computer, and in the future it's possible some of them might offer insurance or other guarantees in case they lose your money.
It's a design feature that there's no administrative body who can restore your Bitcoins. You would have to trust this administrative organization not to abuse their power. The developers of the original Bitcoin client have no more power than anyone else using Bitcoin.