Would my box elastics for a Posterior Open Bite pull my mandible back? (photos)

While it is possible to damage teeth during removal of braces, it is unlikely, unless you're trying to do it yourself.  Removing braces can compromise the enamel, but this can be corrected using bonding.  If you are having your braces removed by a dental professional, then I would not...

I would recommend trying to put the retainer set back in place.  If you are having difficulty doing this without pain, it is best to put it in place at night, just before bed and then going to sleep.  This helps for it to naturally just move into place during the night, as you sleep....

Unless you and your dentist have worked out something different, dental bonding is usually not included with your Invisalign costs.  Every dentist is different, so it really depends on your specific case.  In my office, dental bonding is billed separate because it is way more labor...