Can snap on sue me for not returning a tool box that they credited to me?

Yes.

Of course. And, they can do more damage to you than that. It belongs to them, not you. Taking an employer's property and keeping it - are you that anxious to have criminal charges brought against you?

prolly

If they have credible evidence that they provided you the tool then yes. If not then let them sue you and you just deny getting the tool. They would then have to provide some proof of their claim in order to win the case.

If you didn't and/or won't return it, they can sue you for the property or its value.

Yes. You basically defaulted on a debt. If you were smart, you would call them and make arrangements before it goes to debt collectors.

Not sure what you mean.

For all goods that are transferred, there should be a matching payment.

if you didn't pay for a tool box, or you didn't buy enough tools to get it as a contractual premium, yes, they can expect to be paid.