Last year, they announced the narrators at the end of July. However, that was when ADRs were 90 days out. Now that ADRs are at 180 days, I've read that they are expected to be announced in late spring (I guess that could be this month). The overall dates are from November 26 to December 30th. The only narrator I know of is Steven Curtis Chapman from December 12-15 (as listed on his personal website, but schedules can change).
As for packages, I would highly recommend one. I've only seen the show from standing outside the theater, and it's not preferable, unless you only care to watch for a few minutes. The standby line to get in without reservations is enormous and it's hard to wait there (with a young child) with no guarantee of getting a seat. As for viewing times, although the first viewing is cheaper (if paying OOP versus using meal credits), remember that it may not be dark by that time. So the effect of choir members holding candlelight may not be as dramatic. And as the other poster mentioned, you may not have sufficient time to get setup for Illuminations (if that matters to you), if you choose the third viewing. Personally, I would get a package for the second viewing, although your own cost and schedule considerations may warrant a different choice!