1. Fixing the problem could potentially grow back some hair, its hard to say. Although considering your family history it is almost 100% regular male pattern baldness.
2. Yeah sure ask them but I would go to a general practisioner for it. Most likely the derm will tell you to go to a regular doctor as well.
3. Okay, this basically confirms you have male pattern baldness and it is agressive considering you started at 17. Finasteride works different for everyonr but currently it is the best treatment that exists for hairloss. It may give you some regrowth + years of no hairloss, it may stop ur hairloss for years with no hairloss, or it may not do jack sh*t. Even how well you respond to finasteride is determined before you were even born so the only way to know is to give it a shot.
Do you have baldness in both sides of the family or is it just your dads side? Does your moms side of the family have hair into later years?