Like many of us, I see you want to take good care of your new baby.
As mentioned above, by @The_Ghost
, confirm the dealer checked Hub bolts (3 on each wheel, make sure they're all there and that they're torqued to spec). The bolts can be marked with a line in white paint so in the future you can see visually if they have loosened.
When do they recommend you change your differential fluid, and why did they omit that? I would think it would be done at the same time as the trans oil change. Could be they are recommending getting that done at same time as axle seal replacement?
They omitted flushing brake fluid. Pull off the cap and see if it looks pale yellow, or dark black. If black, make sure it gets flushed, at the latest when you have your brake pads next replaced.
They also omitted the coolant flush. Why? Do you have a record of when it was last changed? Did they test the coolant for ph and electrical conductivity?
Dealerships love to pour bottles into gas tanks, that is a service item they never forget, and it is especially useful on our direct injection engines. Looks like you got 2 done. But I gotta wonder about they're doing a "throttle body service" on a direct injection engine. I think all it sees is air that has already passed through the air filter. Maybe someone with more experience than me can comment if they have every seen anything needing cleaning in the intake and throttle body area.
Our fuel pumps normally make a clicking noise.
A "generic part" worth changing on the GXP is the engine management software. I am purchasing the Budget Trifecta tune for my new to me GXP. Only costs a couple hundred and helps a lot with performance.
For sound improvement most here on this forum recommend a Solo exhaust or perhaps a V8 installation if you have such ambition. Others, like me, are more likely to leave the exhaust stock and upgrade the door speakers.
I see @The_Ghost
also mentioned changing steering fluid. I'm looking for more info here on that one. How often to change it (miles or years) and is there a certain type and brand (synthetic?) fluid recommended? If I look at mine what color should it be for OEM fluid?