I've done bucket loads of research on nitrous. I've wanted it ever since watching mad mad 2 with my dad as a kid, and asking him, "Whats that Dad?"

I actually fitted it to my drawthrough supercharged pushrod japper, but one week before The meeting I was going to try it at, I melted a piston. So now If building a temporory motor which will get the bottle.
Some of the basics things are,
Run less timing,
100hp shot MAX with hyperutectic pistons.
You must have a good fuel supply. A fuel pressure drop will cause a lean out=engine death.
Spark plugs that that have a thick earth strap so as not to get too hot and cause pre-igntion.
Solder as well as crimp your wiring ternimals.
Run one bottle per stage.
The farther from the port a fogger is placed, the harder it will hit.
Don't ask a stock motor to handle too big a shot.

The horror stories you've heard will be as a result of poor tuning, or badly set up installations.