Congratulations on having you orthodontics finishes and having you implants placed.

The questions you are having should only be directed to your treating dentist. It is impossible to answer this over the internet without looking at your x-rays and course of treatment. Typically, a retainer can be readily modified to allow for implant healing abutments and temporary implant crowns can also be readily fabricated to maintain the space properly. But again, this is left up to your dentist who knows you case. Please call your dentist as soon as possible.