1 if used correctly nitrous is actually less wear on your car than a turbo. think about it if you are boosting and adding an extra 50hp to your car at all times it's a lot more wear on your internals and transmission than if you're running an extra 50hp only once in a while and only for a few seconds.
2 in the olden days before computers and stuff you would have to spray nitrous with a stupid red button and if you did it at the wrong time you wouldn't get enough fuel cause detonation and blow up your pistons, but nowadays most kits come with auto activation that prevents idiots from ruining their cars and also are more precise so the amount of nitrous you get is consistent and calibrated, so blowing up your car is not really that much of an issue anymore.
3 wet is much more safe than dry kits. a dry kit is dependent on your stock fuel injectors to offer the fuel it needs to go, while a wet kit uses a nitrous nossel and a fuel nossel to provide fuel and nitrous at the same time, this helps to prevent detonation, something that happens when you are too lean.
4 the way nitrous works is by adding more O2 to your engine, it's safe because the O2 is bonded to the nitrogen until it's heated to about 500degrees then it breaks off and can be used for fuel in the combustion chamber. This is why you wouldn't want to spray liquid O2 into your car because the tank could be very volitile and explode easily.
5 you need colder spark rated spark plugs as a safety and performance factor, they don't give you extra HP, but the colder plugs are able to handle the increased combustion chamber heat caused by the nitrous. colder plugs run colder they disipate heat to the engine block better than hot plugs. you want to have the correct plugs for your vehicle though, because they also won't work if they are too cold, but if your going to be using nitrous to compensate for hotter combustion chamber heat a slightly colder plug is a good idea.
6 I don't know a lot about the specifics of our car and what kinds of things it can hold up to, but if you can boost 75 hp safely then you can probably nitrous shot 75hp safely. the only thing about the wet system that would be a concern is usually it's one nossel at the Intake
near the throttle body. you might run into issues with the fact that since it's not directly injected into each cylander it's possible that different cylanders could get different amounts of power if the fuel mixture to each cylander is uneven. this could be bad, the best way would probably to have a computer that knows when your shooting the nitrous adjust your injector duty cycle but I dunno if this could be done with the e manage or the power fc.