if installing anything on a mac and something goes wrong it's almost always going to be a problem on the OS side
By default, 10.6 should be able to run 32 bit and 64 bit apps in the same environment, as the kernel can boot in 32 bit mode and run 64 bit apps if required.
there's more to it than that. it also depends on what was used to write the program
apple dropped 64bit carbon framework support, in short (and fairly inaccurately) that's the thing that lets people build programs compatible with both windows and apple without having to change lots of code.
so programs like photoshop can't use their 64bit powers unless it's re-written in the other framework. And i imagine the programs have a lot of code (given how big the dmg files are) so it may be a while to re-write
that's a "Ch" pronounced as a "K"
Computer skills I should have:
Maya, XSI, Photoshop, AfterEffects, Motion, Illustrator, Flash, Swift3D