Every transaction is traced back to bits that represent newly generated coins. They reside in the blockchain as well.
Again, no. Even the block reward is just another special transaction. There are no bits that represent a bitcoin, or fifty.
And the "value" entries in a transaction? E.g., the "50.04750000" in tx "fd207092f921894229388b6b7a0bd5b1f3e30a50629ad2001f09a0e5657faaa4" inside block 171903 as found here:
http://blockexplorer.com/rawblock/00000000000002901eeaa9c60f32ba02de5089cb44db71bacccbb850ec0c4bfdDon't those numbers somehow represent the amount of Bitcoins being transferred? Although they do not address any individual/unique Bitcoin, I do not see that this would cause a problem as with other fungible things I shouldn't / wouldn't care either?!
Cheers
txcoin