I've had really good luck with the Bougicord brand, I believe that they are OEM.
The recommended spark plug gap for a 1987 Volvo (all models) is .028"
They should be under the top cover of the engine - no spark plug wires, only some kind of springs that make the contacts.
You can tune up your Nissan by replacing the spark plugs and spark plug wires. You should also replace the air filter and the oil.
0.30
.30
gap is .028
spark plug gap is .028
Yes.
There is no benefit
A Honda CRV tune-up should include replacing the spark plugs and spark plug wires. The tune-up should also include changing the oil and the oil filter.
.040
0.045