Re: Contacts strange behavior
I'm not sure if your reference to Google Storage is the same thing I'm thinking of. Go to contacts.google.com on your computer browser--do you see all of your contacts there? If so, then all of the contacts on your phone are probably synced with your Google account.
To be sure, open the Contacts app, tap More>Contacts to Display, and see if you can choose between your Google account, your Samsung account, and the local Phone account. First choose the Phone account, and see if you have a lot of contacts there. Then check the Samsung account. If neither of those accounts have any important contacts, then they're all with your Google account. This means you can Clear Cache/Clear Data from Contacts and Contacts Storage (as described in my previous post) without danger of losing your contacts.