Hi,
With regards to your question, overjet and overbite are 2 different things. Overjet is the horizontal distance between your upper and lower front teeth and overbite is the vertical distance between the upper and lower teeth. In general, invisalign is better at correcting overjet, but can help with overbite if the right attachments are used.
In your case, where you are missing teeth, have baby teeth and will ulimately require implants to replace them, it would seem that braces are the best option. Without seeing your case and records, it is hard to give a definitive answer, but the best way to align teeth and get the proper root position needed for implants is with braces, and not invisalign.
As far as your other questions about the treatment option suggested to you about moving the premolar into the canine space, etc. I would need the full set of records to comment on that as there could be a few different treatment options for you.
