Bitcoin doesn't have an "operational cost", you'll need it if you want to "mine" for profit (not to help the blockchain but the blockchain benefits from you). And that expenses wasn't directly used for generating bitcoins in the network, literally, the Bitcoin blockchain can generate the same number of coins everyday using a single Pentium I computer.
The Price is pure speculation, it's 0 if no one uses it, $1+ if used and $20,000 when hyped.
A miner can have a 1TH of mining power, but the competition is too tough that by computing his chance, it will be decimals percentage.
A miner with a 1TH of mining power can join a pool which could secure his "wagered" Bitcoins at a standard rate. Now you need a different formula for pool miners.
BTC/day = [(β · ρ)/(δ · 2^32)] · sec(hr) · hr(day) (1)
1,800BTC.
The difficulty always changes depending on the total Hashrate of the previous block.
That is to maintain an average of 10 minutes per block.