simple nitrous questions

No problem. Yeah, you should pop off the distributor cap and take a look at the rotor & the tabs on the cap to make sure they are corrosion free and not too dirty. You can take some very light sand paper &/or alcohol and q-tips and clean the connections. I know you probably don't want to take your plugs out again, but I talked to NOS directly a few months ago about plug gapping and they said you can easily put them at .045 without having to worry about it. Plus you have an aftermarket ignition so there is no way that the spark is somehow going to be snuffed out by the incoming nitrous. And since you are probably like me, and only use your nitrous every once in a while...you really want your combination in tip top form for when you are running on motor too...so theorectically you could be losing a very small amount of power (on motor) by having the smaller plug gap, which really is only necessary when you hit the juice. But with your 75 shot...you could easily open your gap up to .045. That may smooth out your acceleration. But the fuel filter is an easy change, and you should definitely change it. All it takes is one fill up with some dirty gas and it could get partially clogged.