1. I believe you can yes.
2. Not sure, I never used Linux except for a LIVE version.
3. For mirroring, I believe you need to have two identical size drives yes. For stripping, I think a difference in size will cause a loss in performance.
ASUS A7N8X-E Deluxe
AMD Athlon XP 3200+
OCZ 1GB Platinum PC3200 Rev2 Dual Channel
ATI Radeon 9800 Pro
Enermax Noisetaker 485W
2 x 80GB SATA Maxtor Diamondmax 10 on RAID 0