*ahem* Wheres your build thread? *stamps foot* We want build threads!

I'll try to answer some things...

A) I'd do it every time I start the machine up. You can either run a homing routine from the software which will use your homing switches, or you can just tell the software "Hey, you're at zero now".

B) My understanding is (and I'm sure someone will correct me if i'm way out) that homing on index just means setting the zero point based on the index (ie reported potentiometer position) of the servo, rather than using an external switch. To understand this, you have to know how the close loop servos work - they have a feedback potentiometer which moves only when the motor actually turns, so if something stops the motor rotating it won't change. This position report is called the index. I realise thats two circular ways of saying the same thing, but hey.

C) ?? I know its on IP-S ?? Surely it will say in the IP-M manual.

D) I don't think it does need them, but they could still be helpful. e.g. when you disconnect your drive motors from the ballscrew, the motor and pot might rotate but the CNC wouldn't move, this would change your index for the home position.

E) I believe hall sensors will require a magnet to be mounted as the sensing object. Take a look at induction switches too.