Re: Zakat Question
In the example you gave, you don't pay zakat on month 0 unless you have had that $1,000 with you for an entire year prior to that.
For year 1 (assuming your year is Ramzan 1 to Ramzan 1), your unused balance is $1,000. You pay zakat on that balance.
For year 2, your unused balance is $2,000. You pay zakat on that balance.
I don't see any additional $500 in the example. You close your year at Ramzan 1st and compute zakat. Not take intervening periods (e.g. Months 3 to 17 etc) and come out with new balances all the time.
Secondly, what I do is compute the zakat on Ramzan 1st, and put the amount in a separate account. I don't have to give all of it away on day one. I try to give it away as quickly as possible, but still look for best sources of utilization. Technically you can keep giving out the zakat money throughout the year to deserved people and causes. However, that doesn't change the fact, that the annual computation of zakat due is made on Ramzan 1st.