Can you just show up and find a camping spot for a few days or even in different spots daily ?? or just overnight camping so basically just ,show up, set up , sleep ,pack up go till the next night ???

When you look at recreation.gov you will see the even sites are redeemable and the odd sites are walk-up only (first come, first served). Max stay either way is 14 days.

Would strongly recommend a reservation. It is a small Campground and very popular.

Yes if there are spots available