1) yes (but)
2) depends on your use, and the type of raid (I am assuming software) simple soft raid0 did not have a lot of advantages vrses the risk of data loss. Makes for cool benchmarks , but normal copying for example wasnt much faster till I switched to fastcopy. normal file stuff didnt matter much, but I needed it for video dual stream uncompressed and other things that really used the drives hard.
Depends completly. let me point out one thing for you. copying From that one single disk TO the other single disk is going to be MUCH faster, than copying Back to itself on partititons or portions of the Raid0 Team of disks having to work together. Because of that I always use 2 or more Teams of disks. so I can be moving the data around without the problem of simeltanious reading and writing to the same Disk or Same disk set. (Without a real raid card it is even worse) Short version: thrashing isn't faster :-)
You should not use green drives EVER with raid of any kind, that said all of my drives in raid are green :-) But you know I like to prove the completly stupid and impossible , as proof of concept :-)
Combine that with using the OS itself to raid , and if you have to go "dynamic" with the disks and all. Combine that with you should always have Fresh new Team of 100% similar drives. the total Sum would be Don't do it, it will still be fun and learning, but nothing good can come of it :-)