ISCV= Idle Speed Control Valve, yes.

With these it's not a case of just fitting it as the ECU has to 'learn' the new valve, it's worth disconnecting the battery for a moment, so the 'KAM' is cleared. (Make sure you have your radio code etc before doing so) if not there is another way to achieve this.

Yes 5W/30 is the correct viscosity, wouldn't have though so tbh, I don't think a manufacture would sell something if it would not work.

I have used non genuine in the past without issue.

Martin