You can check eligibility for trade-in - and obtain an estimated trade-in value for your devices - here:
Apple Trade In - Apple
Transferring data between like devices is relatively simple. You simply create an iCloud or iTunes backup - and restore the backup to the new/replacement device - either during initial setup, or after:
Restore all content to iPad from a backup - Apple Support
The technicians at the Genius Bar of your local Apple Store will often be able to assist with the transfer process - although making an appointment for your visit is advisable. Without an appointment, there may be long waiting times for walk-in assistance:
Genius Bar Reservation and Apple Support Options - Apple