Got Data Sense. No FM radio that I've found yet - maybe I need an app for that.
I've had a 64GB SD card in my 521 since I've had the. 521, and it's worked fine so far.
No glance screen under display settings yet, but this link says it will come after you get Amber.
30gb now, but I've had it as high as 50 in the past.
Glance screen is not coming to 521 unfortunately.
It says so on your link:
Due to hardware restrictions Nokia Glance will not be available for Nokia Lumia 520 and 521.
If you flashed your phone with GD2/Amber then the updates you are seeing would be normal.
I just checked and no update for access point, wificalling, audio, display, etc..
Checked T-Mobile 521 Support page still no word on when they are pushing the updates out
checked nokia servers still have current version not gd2/amber that was pulled that is posted above on dropbox and mega.