Pecanfan wrote:
1. How do you go about drilling big holes in RSJs?

How big?

Not sure yet, but say 10mm holes through 8mm RSC.

Standard HSS drill.
Not a blunt one.
It'll do several holes with any electric drill.
If you want to do many holes, the drill should be going under 500RPM,
and you should use oil, or you'll burn out the drillbit.

(spray-on cooking oil is acceptible)

Be careful when close to break-through.
If you are pushing too hard, then the bit can catch, which may shatter
the bit (unlikely, but wear safety glasses) or more likely really
hurt your wrists.

If you want to do many holes, then buy some 5mm drillbits, and use
these to make a pilot hole.
This will also let you locate the hole more accurately.