For some reason I have a feeling I might miss two options that I didn't order-
the xenons and the adjustable backrest something or other...

Does anyone know how much more expensive it is to get these installed at the preparation center
once the car reaches US soil but before it is delivered to me? ED not :( withstanding...
Is this something they even do? Is there a chance that it can still be considered a factory installed option?
It's only another $1K, but I'm assuming if I get these installed at the dealer later on (if they can be retrofitted), they'll kill me on the labor...

Anyody know...?

I don't know if either the dealer or preparation center will do it. I know you can do it yourself, but it's much more than the $500 option...

You need headlights, ballasts and the mechanicals for the auto-leveling mechanisms. Plus, you'll have to have the LCM reprogrammed to work with the xenons as opposed to the halogens.