iPad Mini 2 will get Retina since everybody and their brother is doing it in similar form factor and at a lower pricepoints. To support Retina, it needs an -X processor with doubled memory bandwidth, so it's more than likely it's inheriting A6X from the iPad 4 of yesteryear. The reason original iPad Mini used A5 like an iPhone and not A5X like the iPad 3 is because the low resolution, just like iPad 2 did not need an A5X. Just like original iPad Mini being a shrink down of iPad 2 it will be essentially identical hardware wise as iPad 4 just in a smaller package, so no need to test against a new configuration.
iPad Mini 2 is not getting Touch ID due to cost as well as it's use of A6X which does not have the supporting circuitry. iPad 5 is getting it though, being the flagship, having A7X and not so tight bill of material.
Touch ID would be brilliant to enable multi-user support on iPad - where it actually makes sense as opposed to a phone, should Apple opt to go down this path. That would be a good enough reason to buy an iPad instead of a couple cheaper tablets for family, therefore get sales which would otherwise go to competition.