<<can i wash the cushion covers of the poptop-bed and the one on the
engine lid? i mean, i know how to get them off, i am wondering if they
tend to shrink and never fit again or something like that. i am just
careful because the curtains have washing instruction but these covers
seem not to.>>

Cold water wash and rinse with "Dirt can't hide from intesified Tide"

Hang out to  damp dry only.

Fit to foam rubber and alow to finish drying prior to installing in the
Van.