Hi,
After some digging I still don't understand some major stuff about Ethereum and I hope someone can explain the following:
1. The miners are executing the smart contract code - right?
Does all of the miners in the system execute all the smart contracts code? And if so, how is the system able to scale and keep writing blocks every 15-17 secs when more and more contracts are being created?
It isn't. General consensus seems to be that bitcoin handles 7 transactions per second, whilst ethereum is about 15 transactions per second. Neither can scale well yet.
5. Bitcoin has a limited number of coins - how does this works here? When are ethers created and is there a limit? What are the rules?
Currently there's a fixed issuance each year, around 15% for 2017 I believe. This % figure gets significantly lower each year since the constant figure becomes a smaller percentage of the total available. This will change when PoS is introduced, at which point the issuance will likely be much lower but at the least is guaranteed not to be higher.
This is a big figure, but is currently not a big factor since it's dwarfed by the increase in demand.