It will experience an inflation rate for the next 140 years or so. It is currently expanding at 50 BTC per 10 minutes. In december it will cut to 25 BTC per 10 minutes, half each 4 years after that.
Bitcoins have already been destroyed to the tune of about 80,000 BTC from disk failures, lack of backups, and forgotten keys. We will already never reach 21 million bitcoins in circulation.
It's a catch-22. While many people would agree that strict deflation is probably a bad idea, the very fact that this policy proves changeable by a popularity vote would set such an immensely worrisome precedent. It would mean that the inflation policy is in practice discretional.
That's what Bitcoin does. The protocol can't know if funds are destroyed... because they cant be. They are actually just sitting in unreachable wallets.
Right, though all wallets are reachable/stealable with sufficient compute power. This is partially why it's always a good idea to split up your holdings into many wallets.