There are many many things to learn, and you would likely benefit from watching some of the Sonar videos that are freely available out there - CakeTV, YouTube, etc., and in addition, there are some REALLY good books commercially available that do a great job of explaining all kinds of things about Sonar, and some of that includes some of the setup stuff - like what hardware pieces do what and why.
Different folks have differing ideas on how to split files and programs among multiple hard drives, and with the speed of current computers, as well as the cheap price for storage, it's really easy to have multiple choices.
The biggest bang for the buck will be to split your programs and operating system away from where your data and content is stored. Meaning, operating system and programs on one disk drive, and sample libraries/projects/ on at least one additional drive.
Some folks split projects and libraries onto 2 different drives too.
If your computer splits the OS and programs on one drive, and the rest is on one additional drive, you should be OK, and if you have performance bottlenecks doing that, than invest in another hard drive and further split off sample libs from projects.
I hope some of the above helps,
Bob Bone