Can a debt collector make hard inquiries on my credit report?

So, yes, everything results in the same point - debt. So, better get rid of it asap. Check out whether consolidation or settlement will be beneficial to you.

Do you check whether or not the debt is valid? If the validate the debt, repay it asap.

Soft inquires are triggered when you pull your credit report. If you owe money to a debt collection agency, then they can pull your credit report and hard inquiries will be triggered instantly. Now, if the debt is not valid and the collection agency pulls your credit report, then you can dispute it.

Yes, of course! Because the collection agency inquiries are hard pulls. So, repeated inquiries from a debt collector can hurt your credit score.