Here at Microsoft we have a high percentage of Windows Phone 8 users (go figure?), however despite this I see so many of the same questions being asked by WP users on the DLs and internal Yammer pages. Here are those questions, and my answers to them. If some MS employees don’t know these things, chances are pretty good that other folks don’t either. Remember, I am not an official Windows Phone spokesperson, and I don't play one on TV. Plus I haven't even worked on Phone for several years now. However I have been an avid user and fan of WP as well as a developer of apps, so I pay attention to things. I may not be able to remember my kids' teachers' names, but I can remember how to unbrick a 920 for example.
Nokia have this covered here: http://www.nokia.com/global/support/software-update/wp8-software-update/Microsoft's page listing the revisions is here: http://www.windowsphone.com/en-us/how-to/wp8/basics/windows-phone-8-update-history
The carrier your phone is currently on doesn’t matter at all for updates, what matters is the carrier it was originally sold by. Go to Settings / About and under Model you will see Carrier: use this to go back to the table above and see when your update is coming. (If your phone is "open market" ie sold unlocked in a saner cellphone market than the US I don't honestly know what it will say here).
First off wait 24 hours. I'm not kidding, pre-GDR3 builds can take a gigantic amount of time for a few folks. If its still stuck, consider reflashing the original ROM image, using the official Nokia tool, downloaded from the actual Nokia site (lots of sketchy sites seem to have it too, ignore them). http://www.nokia.com/us-en/support/software-recovery/ Note this will wipe all data from the phone, which is why it is important to ensure everything has sync to SkyDrive etc. before taking an update.
First off get GDR3, a pile of work was done for Bluetooth there. It also has a new option to work with cars that don’t quite follow the Bluetooth spec correctly. (See earlier post from me on this here http://blogs.msdn.com/b/andypennell/archive/2011/09/27/car-head-unit-compatibility-with-windows-phone-7-5-mango.aspx).
Firstly reboot your phone as sometimes that doesn’t happen automatically after an update. If that doesn’t help, download and install a new keyboard layout. I know this sounds crazy, but it always works.
Yes, its what I use every day, so long as it’s the AT&T or Rogers version of the 1020 (due to LTE radio frequencies). I got mine when it came out and unlocking it was easy (via eBay), but it isn’t so easy these days, and I'm not going to detail on any of that, because I don’t know the current state.
This annoyance was fixed in the Black firmware update.
Please don’t post additional questions below, as I probably don’t know the answer and/or I am not a support service. I just don’t like repeating myself, that's all. Hope you find this useful.