Also to some more of your questions. My gantry was built from steel and I've regretted doing it ever since. Far too heavy and aluminium would of done the same job with ample structural rigidity. Proximity sensors are much better than mechanical switches, break out board wise if it has a parallel port if you want to connect to modern computers just buy a UC100 connector and all your issues will be resolved but make sure it's the legit one and not a Chinese fake one otherwise it ain't going to talk.

I have got a post talking about my gantry on my build post if you want to see why steel was a bad choice by me.