Tickets aren't on sale. Pretty sure those are potential prices on tickets when on sale.
If you click on a seat it re-directs you to a payment page. Surely it would only do this if tickets were for sale.
Not necessarily. Seat geek are a site who advertise personal seller's tickets.
I can easily create a listing on their site under a certain event and sell the tickets despite not actually having them in person and hoping that I actually get them.
When you list the tickets you had to agree to certain terms such as being able to send the tickets out a few days before the event.
I'm sure some sellers tick the box anyway in the hope that they get the tickets and if they don't the order will get cancelled and probably nothing more.