Q: Change Apple ID without losing info

You can change the email address associated with your existing Apple ID. Apps and media purchased from iTunes are permanently tied to the Apple ID used to purchase them. If you create a new ID instead of changing the existing one, you will not have access to items purchased with the original.

Yes.  Sign in using your existing Apple ID, here

https://appleid.apple.com/

This answer is not complete.  If your Apple ID uses an icloud.com email address, you probably can't change it.  A lot of people have found out "the hard way" and are stuck wishing they had not used an icloud address as their Apple ID.