Not much has been released on the Pokemon Bank, but I can answer your main question and not your others. Sorry :/
When downloading Pokemon Bank, you receive Pokemon Transporter which allows you to transfer Pokemon from your Gen V games (Black+White, B/W 2) into Gen VI (X and Y).
Available in January, you'll get a free trial Jan 1 - Jan 31 according to Serebii (are there 31 days in January? :1)