it appears your canines are in the place of your lateral incisors. And I have seen some patients like this that look good and some that didn't look good. It's completely up to you if you like your smile or not. It's not necessary from a dental stand point it's a cosmetic decision. If you are happy leave it alone. If you are not happy I would bond first to see if that makes you happy which is the least invasive procedure for your situation. Good Luck !!
yes you need to go in to have the temporary crown repaired because if you don't contacts can shift and opposing teeth can erupt. Also the gums can tighten around the tooth to make it extremely difficult to fit the crown being fabricated.
In your specific case you are a Class III skeletal bite where your lower jaw is in front of your upper jaw if that is your true bite. So your orthodontic problems are more skeletal than dental which only about 10% or less of the population have.
most likely not because the retainer is not fitting correctly since the braces have been removed. The retainer needs to be adjusted.