Which is the quantity of bitcoins that a miner gets for mining a block? Does it change over time?
Thanks

I know the blockchain is the chain of blocks which contain transactions, a hash, and the hash of the previous block (Correct me if I'm wrong). Now, to 'create' a block do you just need transactions that don't fit in the previous one or you need to 'mine' it? The real question is how are blocks created? Do they need maintenance? Why?
Thanks

Recently, i saw on a web page the timeline of Bitcoin. The first point was: '2009. January 3: The first 50 bitcoins are mined by Satoshi Nakamoto, the pseudonymous inventor of bitcoin.'
Now, my question is: Is this wrong or Bitcoins can really be mined? Or are the blocks the ones that are mined (solving the mathemathical problems (hash))?

What is the coinbase transaction and how does it influence in the transaction? How does it relate with the amount of transactions that fit inside a block? Thanks