I don't know pricing on any of this stuff, but I can pass along some general knowledge.
XM allows subscription to just radio, just traffic, just weather (I don't remember if LEAF has weather - I don't think so) or any combination. Prices will vary based on content. Nissan/XM provide 90 days free from sale date. XM will contact you to offer a subscription package prior to the end of 90 days. If you say no thanks, they will likely offer you a better deal either then or in the future.
(If memory serves, everything might be ~$20/mo)
CARWINGS is all the telematics stuff, which is different than the navigation system. It will provide
some info that will be displayed on the nav screen (ie: charging locations), and will do all the other stuff that is posted in the new CARWINGS info post. Apparently it requires a subscription. My guess would be that the subscription would go "active" when the car is sold, and it would be three years from that point. Subscription info ahead of time is to make sure that you and the car are in the system most likely to avoid last minute issues. (Wildly speculating here as Nissan does not offer this system in the US yet.) After three years will have some currently unknown annual cost. Not required, but if you don't have it, you lose all the stuff it does.
Navigation data itself may be updated on an annual basis, although you will not be required to do so. Current Nissan hard drive navigation systems require the dealer to update the nav data.