i586 should work fine. Don't know the difference between Madrake and Mandrake Cooker. Yes, there are 11 CDs worth of terrain covering the entire world, however, you can download a 10X10 (degrees lattitude and longitude) section of the earth from (Under worldwide scenery from the main menu)
You just click on the section of 'Earth' you want. Get it running first though.
As for whether to go with the cooker 9.3 or regular 9.2, tossup? Couldn't say.
FYI. Any RPM that has .src.rpm in the filename is the RPM that required recompiling. i386.rpm,
i586.rpm mean that they are already compiled (against i386 or i586 processors).
Edit: i.e. 386 or above should work, or 586 and above should work :edit