how to wire clutch switch
 

one wire goes to chasis (neg.) and the second directly to ecu pin ? should there be any resistor, relay, fuse or something ?

and also, when the clutch pedal is pushed down, ecu pin should be grounded or vice versa ?

I have this second wired directly to ECU and it works like stock. Nothing else I didn't do.

what about second part of my question

I didn't do anything else

Just wire the positive wire to the ECU and if you're worried about the ground, run a wire to the firewall or somewhere to ground it close by. You should be good then.