This is an awkward process, not because it's hard to make the hole but that it's hard to place the hole accurately. It's not easy to start the hole accurately and because it's thin, tough steel there's a risk of snatching on breakthrough.
This is a much over-rated process. Your sheet has a heatsink, the drill bit is a thin wire. In a rate to softening point, the drill is likely to lose. It works, but it's very hard on your drills. Use an small masonry bit to anneal the spot instead, then drill with a cold twist dril.
Not for ages. But these drill bits are just M42 grade HSS, which you can buy at good (i.e. industrial) toolshops. They're usually silver, not black and never gold coloured. They are _not_ blue or rainbow coloured - those are cheap knock-off "cobalt coated" bits and are worthless.