2/ Among other things, money solves a coordination problem. Trading a single good against others solves the combinatorial explosion of a barter economy. It is a scalability solution that allows coordination across large groups of people.
12/ Thanks to everyone who helped with this piece: @Croesus_BTC, @FriarHass, @citizenbitcoin, @skwp, @joernroeder, @SwanBitcoin - and thanks to all my supporters. I wouldn't be able to do this without you.
3/ The two basic forms of money are ledgers (made of information) and physical tokens (made of atoms). Physical tokens keep track of themselves. Ledgers need someone who is in charge.