Non-working/improvable things

It won't? You should just have to remove the existing one and attach a new one then save.

I do need to change the interface for it but I could swear it worked as a regular user when I tried it.

My current one is gravatar. It doesn't want to change but still the image is uploaded onto server.

I messed with some stuff - try changing it now (I set it to 2.png, but still see if you can do anything).

- after removing it it went into blank / default mode instead of gravatar
- uploaded new one, still doesn't work

Which browser are you using?

I'll restore your avatar. Not sure what's going on here.

Firefox 25.0

did you reenter your PW as the green box told you? (right now its needed whenever you change something on your profile)

Yep, it seems that this is the case. Green "Passwords can't be empty" is not good wording for such error. I would suggest changing it to red box with "Please enter your current password to save any changes made" (or something similiar to that, I'm not native speaker).