Welcome Nina, lovely car. LY is so amazing, especially in the sun!
Regarding your anthracite pack, if it was me, I'd leave it as is and see how you get on. That's a super rare option so it's nice to have something a bit different. If you do decide you have to change it, as Antti said, I'd definitely just get it wrapped as then you have an option to return the car to its original specification, which is a definite help come resale time.
As for the seats, SPG are a GREAT choice, much better than the more often seen Pole Positions in my eyes. Be aware there are two different sizes, a regular and an XL. Regular are pretty snug even for a relatively slim person. Great seats!
Presume you're pulling the back out too if you're thinking about fixed seats?