I have a 50 amp GFCI breaker in my subpanel box to be used by a hot tub. I noticed that the breaker has a post for the neutral wire load. Is it necessary to use this post or can my load neutral wire be connected to the neutral bus (same as breaker pigtail and supply neutral)?

No Load nuetral must be put on the breaker not the bar. Most spas have a 240v 4 wire system, because some componants run 110v, you need a neutral.