"50 BTC at the moment, will be decreased in the future"
When will that happen and who will decide it? Or is it hard coded in the model based on some calculation? Please enlighten me

The 50 btc is cut in 1/2 every 210,000 blocks. Each block lasts 10 minutes (on average).
Edit: you can also monitor the total # of BTC here:
http://blockexplorer.com/q/totalbc