Hi,
So, RAID 0 is the fastest choice, but it's really dangerous. If you have a trouble with one HD you loose EVERYTHING! Raid 10 or RAID 1+0 or RAID 0+1 are a combination of RAID 0 and RAID 1. These combinations cannot be made with only 2 HD, you need at least 4 hd (RAID 1+0) or 3 hd (RAID 0+1).
Question 1: Yes, you can BUT you need at least another HD, honestly I prefer RAID 5...
Question 2: Yes, there's but everything depends on your hardware. RAID is set up via a direct controller (raid controller) or integrated to the motherboard (usually pooooor performance). There are also software raid, but trust me, don't use software raid... usually you can set up things after the POST screen (F6 or F10 or F something).
For you last question: usually it's configured BEFORE, then you install windows and Windows will see only ONE hd (because of in a RAID 1 there's a mirror), if you use software raid, you can install it AFTER.