1) If I hold 1 million Blockshares out of the 900 million, will I receive 1/900th of the transaction fees as a bitcoin dividend?
If you hold 1/900th of all BlockShares, you will receive 1/900th of all Bitcoin dividends (this will be
very slightly skewed by the fact that some of the dividend will be used to pay Bitcoin transaction fees to transfer the dividends and nothing will be sent to BlockShare owners that would receive less than the Bitcoin transaction fee).
Dividends are not tied directly to transaction fees. Rather, they are tied to the number of BlockCredits sold (which can only be used to pay for transaction fees).