A unified call would be nice, but everything you asked for falls into one of 3 categories:

1. It's already in the users/{ids}/associated call.
2. It's trivially easy to calculate in the app or script. EG: Total reputation and total badges.
3. Or, it's the kind of information that changes very slowly and should be heavily cached by your app/script for at least a day.

So the first time you see a user-id, you have to make a few extra calls, but after that your app can, and should, pull that data from its own storage.
Just update it if it's more than a day old, or better yet, only if the user explicitly requests it. (For most users, their non-numerical flair data is unchanged for years at a time.)

A unified call would be nice, but everything you asked for falls into one of 3 categories:

1. It's already in the users/{ids}/associated call.

2. It's trivially easy to calculate in the app or script. EG: Total reputation and total badges.

3. Or, it's the kind of information that changes very slowly and should be heavily cached by your app/script for at least a day.

   So the first time you see a user-id, you have to make a few extra calls, but after that your app can, and should, pull that data from its own storage.
   Just update it if it's more than a day old, or better yet, only if the user explicitly requests it. (For most users, their non-numerical flair data is unchanged for years at a time.)