No.
yes
yes
yes
yes
yes
No they have no skeleton or exoskeloton
yes
Endo (inside)
No, worms do not have any skeleton at all.
Molt off the old one
Endoskeleton - they are vertebrates and their bones are inside!
Hermit crabs and some insects do
Yes they do, and periodically they are shed so that the spider can grow larger.