Not sure what this bigger one is either. What will it do?

Not Mammillaria. but not sure what genus this little one is, which direction to look? Will this do anything exciting?

Noki,
The one in your first photo is Mammillaria spinosissima, AKA red-headed Irishman. I believe the color of the spines is variable, some are more red than others, some more have more white in their spines, etc. Sorry, I don't know about your other Mamms.

Planto

I think the second one is Parodia erubescens. It has a few other names. Here is mine in bloom. I will look for the non blooming picture. The problem with taking so many pictures is they get burried and then I can't get my hands on them when I want it.

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Here they are. Second shows the buds just starting to form. If you click, the images will get bigger. The better to see if this is the same.

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Your last one looks like Notocactus buiningii.
And what do you mean by "exciting"? Its a cactus, not a toy.

Exciting as in actually grows, has cool flowers... just doesn't sit there and waits to die.

Last one does look like Notocactus (or Parodia) buiningii, just the spines on mine are darker than pics I look up.

The Parodia erubescens really does seem to match mine little red one a lot, there hasn't been any sign of a flower yet. I was way off guessing Mamm.

The left one in the first pic... Mammillaria magnifica -? A clumper?

Sorry Noki, but I have to laugh at your comment, "just doesn't sit there and waits to die." That's a way of putting it! :)

Planto