I would personally not advise death gripping the bars. It’s an easy way to lose all the skin on your knuckles (which, to be fair, might be preferable to breaking a bunch of bones). You could get some reinforced gloves to prevent that though.
I think most people do usually put their hands down to keep their face off the ground, but you want to keep your hands as far forward as possible. Ie slap the ground with flat palms rather than stick your arm out to the side like a pole jamming into the ground.
The absolute ideal would be to look to the sky and fall on your back, then immediately roll. But that’s so sophisticated - I’m not sure if I could develop that reflex on the road. I’m sure many MTBers (seth’s bike hacks?) have done so, though. Could be worth looking into.