Family Sharing between two iPad Gen10

We are just about to setup another iPad Gen10

Make sure you have separate Apple IDs for each of the two owners. If you have one Apple ID the two devices will behave as if they belong to one person because they are using the same account.

We would like apps that were purchased on the first iPad to be available on the second without having to pay again.

Family sharing enables members to share apps bought from the App Store (there are rare exceptions) and where purchase sharing is turned on. This should be set automatically, but if not see How to share apps and purchases with your family - Apple Support

We would also like individual iMessage for each iPad.

The Messages app is dependent on the iCloud/Apple ID account used for the device - if you have set your two up with different accounts then Message will be different on the two.

How can I go about setting this up?

Set up Family Sharing - Apple Support