I do all the cooking at our houe and have for over 39 years. So I do know a bit about it. Most of the time if your crappie is soggy it is becuase your oil is not hot enough. It should be about 370 degree's. You will know when your crappie is done (Or anyother fish) when it is golden brown. Do not try and cook to much at one time as it will lower your oil temp and again make them turn soggy. If cooked right you should not have oily fish. It should be crispy on the out side and flaky on the inside. Take your oils temp and you will know when it is ready. Or buy one of the deep friers that have the readout on them.
As far as battering goes there are many way's to do it. You can roll the filets in corn meal and what ever or you can dip them in beer batter it dosen't matter. If the tempture is not right they will not come out well. Hope that helps a little. Ron