-No, there should be 1 master and 1 slave on each cable.
-It doesn not matter in wich order, unless when you are using "cable select" the drive wich you want to boot from has to be on the second connector
-no, it does not matter.
I suggest this setup to prevent problems:
Primary IDE: 1 master HD with OS on second connector (from MB)
1 slave HD on first connector
Secondary IDE: 1 cd-rom as master on last connector and 1 cd-rom as slave on first connector
Please post your system specs