Wrong on every detail.
1a) Using the "move" RPC command, bitcoin makes an instant transfer between two accounts that you control.
1b) All transactions are published instantly, and available instantly, via the bitcoin P2P network. There are also several websites like http://mtgox.com/ which facilitate instant transfers. After that, you wait on average 10 minutes per confirmation, each of which makes your transaction exponentially more secure. While not recommended, yes you can spend zero-confirmation transactions.
2) Did you bother to look at Android Market before posting? Only full nodes require the full block chain database (2+ GB now). Lightweight software exists for phones, or you can use a web wallet from places like http://blockchain.info/ or http://instawallet.org/
- jgarzik, bitcoin core dev
Incorrect. Even if you have 100% of the network computing power, you still cannot force core rule changes upon users.
Each P2P node validates transactions and blocks on their own, and refuses to relay invalid ones. Deviating from these rules simply segments yourself away from the rest of the network.
With sufficient network power, you may DoS the network, but not force unwanted rule changes.
- jgarzik, bitcoin core dev
Ya'll hear about the geometer who went to the beach to catch some rays and became a tangent ?