monster/mon-init.c memory free bug

Fix clearly misplaced line of code (fb should be initialized outside of the while look), explicitly initialize pointers to NULL for safety and reduced gcc/clang warnings.

Also, minor style for previous quark-free patch: should check for ">" not "!=" for safety (it's not clear that the 'if' statement is really needed, if the 'for' statement is already comparing for '<').