Re San Andreas (as ever, always get copyright holder's permission first...), just in case you've not looked recently, Gensis has a few working HD links.
Regarding the hardware acceleration settings, start from Kodi/DBMC/XBMC/SPMC's homescreen, and look for the System menu then click it. No system menu? Try Settings instead.
Now click on the Video entry, and make sure Settings Level (bottom left) is set to Expert or Advanced. Now select the Acceleration entry and follow the advice David gave you previously.