Wireless charging usually gets a bad rap for being slow, at least compared to regular wired charging, especially with phones feature fast charging abilities these days. However Apple did state that they plan to boost wireless charging speeds with iOS 11.2 and sure enough they have with the latest update.
As for Apple Pay Cash, this is basically P2P payments made using Apple Pay. Users of iOS and Apple Pay will be able to send each other money using their linked debit and/or credit cards, a feature that has been missing on Apple pay for a while. Other companies have already allowed P2P payments, like what Google has done with Gmail, and what Facebook has done with Messenger.
The update will also fix a weird December 2nd bug that causes iPhones to soft reset. The update should already be live so keep an eye out for the prompt, or head on over to the Settings and pull it manually if you can’t wait.