If that RAID 0 array isnt a lot faster, I will be surprised. It will deliver close to 2X the read/write speeds of a single drive. I have run RAID 0 for years without a single loss.
But, since it CAN happen, always keep a backup of files you cannot afford to lose.
2. Doesnt matter - I have done both.
3. Stripe size - most say go for the largest which is usually 128k. Do 128k or 64k. You pick.
4. Quit over analyzing and get on with it. Seriously, these things return so much performance for just doing it. Do keep backups of important files in case you are one of the few who's RAID array fails.
Go have some fun