MT,

1.  I usually used peanut oil.  This past year I brought coconut oil as a healthier and more flavorful alternative.  The negative of coconut oil is that it moves from liquid to solid at around 80 degrees F.  So you may need a spoon to get it out of the bottle...or not.  Nevertheless, love the flavor so I'm making this a permanent change.  Always though, I use some squeeze margerine as well as the oil...roughly 2/3 oil to 1/3 butter.

2.  Type of skillet?  Sure, heavy cast iron would be the best, but I'm not carrying that and I suspect neither are you.  I use a non-stick skillet.  There's a lot of variablility out there on non-sticks.  Some aren't worth the coating they are sprayed with.  Others are quite nice.  I have a couple that I regularly use.  One is a GSI w/ folding handle.  One is an old nonstick kitchen skillet of indeterminate origin with the handle removed.

3.  Grease is less-than-smoking hot.  It should bubble vigorously when the fillets hit the pan but no need to scorch the oil.  Your fillets should come out bronzed, not blackened.

4.  I like Zatarains Blackening seasoning.  Also Lemon Herb spice by McCormick is good.  Or simply sprinkle with dill, salt, pepper and then squeeze lemon over the top when removed from the pan.  Or any of a variety of dry rubs from the supermarket or butcher shop can be good.

Mostly, though, just experiment.  Try it on the home stove to get your technique down, then move to a campstove to be sure you have the right pan and learn the proper flame setting.  Or just wing it and use your campmates as guinea pigs, like I usually do.