Answer:
Soldiers fight it but never changes.
What sphinxes employ and players enjoy.
This is meat from the upper part of a pig's leg salted and dried or smoked, often enjoyed in a sandwich.
What is something yet nothing, but if you fill it up it will disappear?
No matter how little or how much you use me, you change me every month. What am I?
Special abilities and brightly colored underwear are all you need to be one of these.