RAID questions

Hello,
I have a Dell 2600 with a PERC RAID 5 using 6 drives. No hot spares. The drives were removed from the chassis without being marked. A couple of questions at this point: (1) is there anyway of determining how they went in originally? (2) A couple of the drives are showing failed, what happens if I force them online?
The server has redundant systems. I think the RAID card channel 0 maybe bad, can I move the drives to the other channel and get the drives to work.
Last the OS is on the RAID, how will this be effected?

Thanks for any input
Kyle