1. Stick with OEM Nissan or NGK, which I believe are the same things.2
2. You'll need a spark plug wrench or adapter that drops down into the holes.
3. They 'should' not need to be gapped, BUT it's worth the $1 tool to check for good measure.
4. Make sure the car is cold, or at least not hot. Don't want to crack one.
5. A dab of motor oil on the threads goes a long way. Don't bother with that diaelectric crap.