None of that runs through the radio.  The radio does not have a switched
power lead like older ones, it has an always on power connection and the
class II data bus tells it to turn on so you will need something to turn on
and off the aftermarket radio via the signal.  Also the chime runs through
the radio so you will need something to provide the chime.  The radio also
has the ability to reset the oil life reminder and other things like that
which are not necessary but nice to have so if you want to keep some of
those features you can get the relocate kit to keep the factory radio
installed somewhere.

You lose any programming items that are controlled through the radio.
You also lose the chimes and warning tones as well. Facts of life with
many new vehicles. If you have any onstar items they are also through
the radio.

two ways to do it, a harness that energizes the old radio that is now put
away in the trunk and the new stereo plays through the speakers, or a Radio
data bus box.

The two kits are about the same price $50-$75 or so and the install of the
data box is easies instead of running the 20ft of wire to the trunk.