Quote from: Nexus9090 on Today at 12:58:22 PM

How big is the total nonce range that a miner has to scan to create a valid hash

32 bits

Quote from: Nexus9090 on Today at 12:58:22 PM

Am I correct to think that the total adjustment range a miner can make is to say (nonce + extranonce + timestamp), a total of (2^96)?

Changes to the timestamp or other parts of the candidate block gives the miner more nonce space to play around with.

Quote from: Nexus9090 on Today at 12:58:22 PM

Also, what determines the starting nonce for each miner. I know there's a nonce provided in the block header, is this what gets used as the starting point or is that for something else?

The miner decides which nonce to start at. If in a pool you can have a nonce range allocated to you.