iPad security questions and app security questions

1) All data stored locally on your iPad is encrypted by default. Your iPad uses an encrypted filesystem; the only copy of the encryption keys, required to access any data on your iPad, is securely stored within the iPad's dedicated security processor (known as the Secure Enclave). Successful entry of the device Passcode unlocks the Secure Enclave and releases the encryption keys to the Operating System while the device remains unlocked.

2) Erasing your iPad from iPad settings performs a crypto-erase. This process securely destroys the encryption keys stored within the Secure Enclave - and therefore ensures that all locally stored data is permanently beyond reach and cannot be recovered.

3) The only additional backups of data or files, locally stored on your iPad, will have been manually created by you. All locally stored data is encrypted. See Answer (1).

If you would like to learn more about Apple's Security Architecture, see:

https://help.apple.com/pdf/security/en_GB/apple-platform-security-guide-b.pdf

As your description was non-specific, I refer to "backup" in the loosest possible sense. I assume that you may simply be referring to copies of files/data that you have saved elsewhere.

This support page outlines the natively supported backup methods for iPad and iPhone:

How to back up your iPhone, iPad, and iPod touch - Apple Support

Native iOS/iPadOS backup and restore processes are dependent upon iCloud, or connection to either Windows PC (with iTunes for Windows installed) or a Mac (with iTunes or Finder - as appropriate for the installed version of macOS).

Natively supported methods offer full system backup - consisting of data and device settings.

How to back up your iPhone, iPad, and iPod touch - Apple Support

It is possible to use a third-party App to backup data (but not device settings) to a variety of external storage options - including third-party Cloud services, external media devices and network storage. One App that comes readily to mind is FileBrowser Professional by Stratospherix:

https://apps.apple.com/gb/app/filebrowser-professional/id854618029

Copying data to external or other cloud storage will not necessarily be encrypted. If you need to encrypt files elsewhere, this an entirely different discussion.