yeah that will work no problem, you can have a raid array and other ide/sata drives at the same time. Tho the only problem with raid 0 is if one drive fails in your array then all data is lost but the chances of that are remote, hope that helps
Yes, setting up RAID and having another drive for storage is totally do-able. The storage drive doesn't have to be IDE, it can also be SATA.
Generally speaking and depending on your mobo and onboard SATA/RAID chip, when you go into the RAID setup, it should see all the drives connected to the SATA controller (unless you've got nVidia's MediaShield or Intel's Matrix RAID which can RAID IDE and SATA together) and thru the RAID menu options, be able to choose the drives to build the array, and then the array type.