How to buy & collect high speed train ticket

Is there any special counter for picking up tickets (取票窗口 or 取票专口) at both Chongqing North and Chengdu east high speed train station for those who have booked a ticket online?

If I already have the e- ticket for the high speed train from Chengdu to Chongqing , can I exchange it to a paper ticket at Chongqing high speed train station (Chongqing North) 12 days in advance ?

Can I exchange the e-ticket for the high speed train to a paper ticket at the railway ticket office inside Chengdu airport 12 days in advance?

Can I buy the high speed train ticket directly at the railway ticket office inside Chengdu airport ? How many days can I buy the ticket in advance?

Is there any railway ticket office (where I could buy ticket for high speed train) at Chongqing Airport?