Installing Sonar 8.5 PE on a system with two hard drives (plus some more questions)

I have a system with two seperate hard drives. I was planning to install the OS on the first one (obviously) and all programs (Sonar, plugins, etc.) on the second one. But I've read some topics saying it's better to install Sonar on the OS drive too and use the second drive for audio and for samples (that come with Dim Pro, RealStrat, maybe EZ Drummer). 

Would it hurt performance if I would still install Sonar and everything else on the second hard drive...? I kinda like the idea of having all my music stuff NOT on the OS-drive, in case I want to re-install the system. Apart from that, I don't really know how (and if it's possible) to install for instance the samples that come with various plugins on the second drive, while the plugin itself is on the first one... (like with Dim Pro, which is installed when Sonar is installed). It seems easier to simply install everything on that second drive, but if this would really hurt performance, that would be a pity...

I have an i7 920 @ 3.3 btw. Right now I have hyperthreading disabled: would Sonar benefit a lot from hyperthreading?

And o yes, another thing: I've read a few plugins that come with Sonar 8.5 are not 64 bit compatible. Is the installer clever enough to know that or do I have to disable certain plugins manually before I install...? (And if so, is there a list of stuff I shouldn't install)?

And finally: I've ordered the S8.5PE upgrade from S7PE: will I get 8.5 complete and all on disc, or will I get 8.0 and do I have to download the 8.5 update?

That's all... for now... ;)