Can a CT with contrast/iv show arthritis and vaginal slings or other mesh, do both MRI and CT show these particular items?

Yes. Yes - they can show mesh, but they are generally not the modalities of choice to evaluate mesh complications. A thorough history, physical exam, and possibly cystoscopy (looking inside the bladder with a camera) are the best ways to evaluate someone for possible mesh complications.
Yes. A ct and MRI can show arthritis. You can also see vaginal slings but they are very hard to visualize.