Hi
By creating a new Apple ID for your wife and then setting up and using Family Sharing, you can each use separate Apple IDs whilst continuing to use all of the previously purchased eligible apps.
To transfer contacts to your wife, you may wish to consider using an app such as My Contacts Backup:
https://itunes.apple.com/gb/app/my-contacts-backup/id446784593?mt=8
If you each also enable iCloud contacts on your devices, your respective contacts will remain synced across your own devices:
- Go to: Settings > iCloud > enable Contacts.
More information:
Create and start using an Apple ID - Apple Support
Sign in with a different Apple ID on your iPhone, iPad, or iPod touch - Apple Support
Family Sharing - Apple Support
Set up Family Sharing - Apple Support