If the tweeter you're replacing is approximately 5-1/2" x 3-1/2", and the cutout in the cabinet is 3-1/8" or thereabouts, then this tweeter should be suitable for your application. Some tweeters can be repaired, however, it's not something that our Speaker Repair Center can do at this point in time.
If the dustcap on your midbass is metallic, you can try a magnet to pull it back into shape. If it's not, I've heard that duct tape can be used if one is careful. Gently apply the duct tape to the dust cap, and then simply pull it off. If you can't repair it through these means, we do carry some replacement dustcaps. I've referenced one below for your convenience.