Watch my video where I give pros and cons to Invisalign. Also I answer questions you may have about Invisalign. These are all my personal experiences with Invisalign and just my opinion. If you would like to contact me for other information please feel free. My video:
It should be fine for you to skip ahead to the next retainer, but just make sure it fits okay. If you can't get it to seat, contact your dentist and have them reorder the broken one for you to wear for two weeks before going to the next one.
The guidelines for what expanded function assistants can do varies by states, but I personally don't think assistants should be doing IPR since it is irreversible.