Rapi:t - Limited Express Super seat

We plan to take the Limited Express Rapi:t from Namba to Kansai Airport with Super seats.

What is the price of the Super seat at the ticket counter?

Can we just purchase the tickets (with reserve seatings) at the ticket counter at level 2F in Nankai Namba station, ahead of time eg 4 days in advance?

Please advise. Thank you.

The cost is explained here:
https://www.nankai.co.jp/en_railway/traffic/express/rapit.html

Tickets go on sale 1 month in advance of travel day, so, yes, you can buy it 4 days in advance.