A family of Microsoft word processing software products for creating web, email, and print documents.
Yes but typically files opened on a word app on your phone originated elsewhere. Chances of losing all your files in the process is low. As you would still have your email attachments and cloud files.
It really depends how badly you want to remove those hard to delete files from your phone.
For me I had a malicious looking file in there so deleting it was more important than keeping my application history.
Make sure you've saved everything you need somewhere outside your phone before deleting application data.