OK, if the board has 2 parallel ide interfaces (p.a.t.a), I say 2 because you will need a connection for cd/dvd-rom, then yes you can use your existing drives.
In the bios there will be a section for selecting bootup sequence a:, c: etc. For scsi just select none.
This info is generic and should be taken as such, I have no particular experience with this board, but most mobos opperate along the same lines.
Yes you will be able to upgrade to raid/sata in the future, if you ment upgrade other parts, that depends on how far in the future and availability of parts.
Hope this helps.