S14 A/T control unit usefulness and others

[bsd]

I have 1995 S14 base model, just finished a 5-speed swap not long ago by someone in nicoclub. No electrical wirings are hooked up yet beside the starting circuit because there are so many different story by different people, some recommend to do this and some don't, causing the confusion.

I also read http://www.ka24development.com....html and further confused.

1) The whole point for completing the circuit of neutral/5th postion switch, is it just to let the ECU not to throw out any codes or are there actually something more to that (essential or personal preference)? any harm?

2) Anyhow, why drill a hole in front of the shifter to run the wires through from the transmission when assuming the following two wires are connected to the inhibitor switch (E13):

a) Can I just cut such wire(19) from the A/T control unit (M21) and run it directly (bypassing the A/T control unit) to the ECM?

b) Can I also do the same for 5th Position Switch?

This way, I don't have to drill a hole near the shifter since those wires appear to be routed from the inhibitor switch to the A/T control unit anyway.

3) The A/T control unit dropped off all the time because I didn't ziptie it tight enough. I now taking the chance and completely disconnect the A/T control unit from its harness and notice one different, which is, the O/D lamp doesn't light up anymore.Any harm driving without A/T control unit? If there's no harm, why on earth nobody else is doing it? Specifically, what's its usefulness after a 5-speed swap?

Thanks for your help.