Conceptual question: Do I contribute to the bitcoin network just by running the Bitcoin-Qt v0.8 client?
If you accept incoming connections (e.g., firewall opened up to your IP) that might give other nodes an easier time of connecting.
A Tx is supposedly trusted after "6 confirmations". Who does the confirming? What constitutes a confirmation? Is it simply when 6 additional blocks have been added to the block-chain?[/quite]
Miners are the ones who include transactions into a block. A confirmation is the name simply for the transaction making it into a block. Blocks are chained together, so that first block plus the next five gives a chain of 6 blocks, each block is a confirmation so that gives you six confirmations.
When I first ran the client, I had to wait several hours for the block list to sync. Is it just that I got the block list from other clients, and that's the "peer2peer" nature of the thing?
That's fast. It used to take several days.
The full set of blocks since Satoshi's block #0 need to be downloaded. That's what your client was doing. Now that your is sync'd, it will share any blocks it knows about with any other peers that connect to you.
