Yes, you may play sports while wearing your invisalign trays. Your best option is to consult with a dentist first to make sure you're a good candidate for invisalign. You should probably wait until after completion of invisalign prior to teeth whitening.
Given the picture, your best case scenario is the crown has come loose from the underlying tooth structure. However, it is most likely the tooth has fractured at the crown/tooth junction. You need to see a dentist immediately to avoid any further damage.
It would be best if we could see the gum line, but from what we see in this picture they look beautiful. The dentist did a fantastic job.
We have found the Zoom teeth whitening to be the most effective. We also offer bleaching trays for home use.
Yes, the invisalign attachments will wear down as you use them. Originally the attachments are hard.