Details please on the improvements from the latest "Carrier Upgrade". Also details on any loss of utility.

Details are seldom given for carrier upgrades. And at any rate, your carrier would be a better source of that info. These do not come from Apple.

That would depend on your carrier.

A carrier update would have no effect on the utility of your phone. It is simply an update from your wireless carrier that you should perform anytime it is available.

And for what it is worth, I have never seen a carrier update have a negative impact on a iOS device.