Far be it from me to disagree with the official line...
... so I won't.
I'll just add that most of the time (GNS430 / 530 excepted) the GPS supplies the current date and time for the screen display (if used) and in the logs.
The alternative method to keep/set the current time is to have to have the keep alive line connected, which is not recommended these days.
Winds aloft is worth having.
I have it on my D100, which gets its GPS data from the GPS connection to the EMS D120, via DSAB.
The OAT probe is worth having for its own sake too.
As well as the already mentioned Winds Aloft and the obvious outside air temp (are you icing?) it allows for TAS and pressure altitude calculation and display.