Ok, by now it's March 2nd everywhere on Earth, so we can't blame timezones
So, thanks for asking.
We have been working hard to get this out on our announced date.
There is a big feature for the administrator area (more at release time) which made it into CB 1.2.2 last week-end, thanks to a very nice contribution work of very high quality from a Joomlapolitan. This is delaying our planed release by 48 hours.
Our (public) CB tracker shows only around 8 more hours of work needed to release.
To quick answer the 3 good questions above:
1. Yes, the API remains compatible to 1.2.1.
2. Quite a few, PHP 5.3 compatibility being one of the urgent ones, more with release notes.
3. Yes, on Joomla 1.5 the upgrade method is implemented, and on Joomla 1.0 and Mambo the "expert"-files overwrite method allows to avoid uninstallation. README and installation manual has already been prepared.
Thanks for your understanding