Invisalign. Invisalign is a clear, removable way to straighten your teeth.
Certainly. Clear aligners like invisalign, clear braces, or lingual (invisible braces) are all options. Seek an opinion with a licensed orthodontic specialist to see what's best for your situation.
Probably not. I am not an orthodontist or dentist, but to my knowledge braces or retainers are the only way to straigten teeth in nearly all cases. Sometimes surgical procedures are used along with braces.