The 0.73 for this game is out: http://sourceforge.net/projects/supertuxkart/
After install you may want to delete/remove OpenAL32.dll as it installed it when I already had a copy of OpenAL.
Changes include more karts, tracks, and battle mode changes in offline multiplayer.
To make the AI easier to beat, you can lower the ai acceleration value in the stk_config.xml file in the data folder. <ai acceleration="0.5" />
The Karts max number may have been 19, but 29 worked good on levels I tried. <karts max-number="29"/>
You can shoot backwards with some weapons by firing while looking backwards.
Here is a site with addons, that also can be downloaded ingame: http://stkaddons.net/
Addons can be downloaded with the default settings, the address:port will have to be allowed for firewalls, you could also manually put them in the appropriate location.