I may be overthinking this - I am understanding that I report bank accounts if during the year the balance reached $10,000 or more. If I receive the equivalent to $2,000 a month into my accounts but spend it so the balance never reaches the threshold then I do not need to file FBAR? It isn't about the $24000 that was deposited over the year?

Your understanding is correct. The trigger for reporting is the maximum in the account(s) during the year. If you have more than one foreign account it is the total of the maximums for each account. If that total exceeds 10,000USD all the accounts must be reported.

That is also my understanding, and the exchange used to calculate the maximums is the one they publish at year end, December 31st.