WooComm coupons_ Expiry vs “Active for X payments”

Hi, I have a woocommerce subscription product that is billed weekly, and I’d like to offer a coupon that will provide a discount for the next 12 payments (ie. next 12 weeks), but only if they purchase the subscription before January 1st. I’m therefore trying to understand how the logic will work between Expiry Date and “Active for X payments”:
1) Will one override the other?
2) Will I achieve my desired outcome above if I set the expiry to Jan 1st and “Active for x payments” to 12?
3) And how is “Usage limit per user” treated differently to “Active for x payments”?

Thanks,
Michael