When OS5.0 is finally released near the end of this year it will include BBM 5.0 and it will have the ability to save your BBM chats to your memory card.
Or you can download the unoffical release of BBM 5.0 and get that functionality now.
Sort of. All Blackberry's use the Blackberry core OS. Different models will run different versions. The Storm and Tour run 4.7 while the 8830 WE, 8130 Pearl and 8330 Curve run 4.5.
RIM will soon be releasing OS5.0. They've "promised" it before the year is out, but they haven't released exactly what devices will get the upgrade. The Storm and Tour definitely will. The Storm 2 will launch with 5.0.
I'm not sure if the 8xxx series of devices even have the hardware requirements to run 5.0. Xtremeberry would no, but he's not around much anymore.
You can save your BBM contacts to your SD card and you can ell it to back up your chats which are both two very important additions to the new BBM 5.0 Right now BBM 5.0 does not work with the new OS 5.0. This is why I uninstalled the 5.0 OS and downgraded back just so I could keep BBM 5. Word is right now that it will not release with OS 5.0 and actually could be up in the blackberry app store. Weird I know but apparently RIM keeps adding things to BBM which is causing it to be pushed back. I cant wait.