Is a Hotmail address the same thing as an Outlook account now?

yeah and you can keep using the hotmail address for everything. if you do add an outlook.com alias, you can make either one the primary for sign-in, and mail sent to both lands in the same inbox.

Pretty much. Hotmail was folded into Outlook.com years ago - your address stays @hotmail.com, but you sign in through Outlook and it's all the same Microsoft account. Same login for Xbox, OneDrive, Teams etc. You can't convert it into an @outlook.com address, but you can add one as an alias on the same account if you want a newer-looking address.