This may help you.
RAID - Wikipedia, the free encyclopedia
To answer a few of your questions:
If you already have data on the drives before setting up RAID, it will get lost.
Configuring RAID doesn't corrupt your PC.
Yes, you need at least two physical disks for RAID. Having one drive with 2 partitions will not work.
With hardware RAID, you configure it first before installing the operating system, you may need drivers. It all depends on the manufacturer of the RAID controller and the operating system.
Graphics cards have nothing to do with RAID.
Nobody uses IDE anymore but the process is similar.
You need a RAID controller and at least two physical disks to set up RAID.
There are a lot of things that can go wrong when using RAID. It depends on what RAID level you choose. The biggest problem is one of the drives in the array failing.