1 These might be beading needles. Are they very flexible, and does the hole at the top squish together?
2 I would say are definitely belt buckles, I have loads in my stash inherited from my Grandma. Be careful though, the ones I've got are plastic, and because they're old they do tend to break quite easily.
3 Haven't a clue, they look a little like beaded beads which I've seen patterns for making. Maybe your Grandma was just experimenting with a new beading stitch.
4 These look like beaded buttons to me.
1 Mm, yes, it does. I guess that's what they are then.
2 Yes, these are plastic, and look like they could break.
3 Hm, okay. I'll find something to do with them.
4 Yes, that should have been obvious, they were near the the box of buttons.... I just didn't figure it out, haha.