Dogdoc- You really need to decide if you want to deal with crappie or not. If you don't want them, then best money spent will be to kill everything off and start over. If you decide to try coping with them, it will most likely mean alot of pond managment to keep them under control. I would guess that every crappie you catch should not be returned, and the rest of the other fish probably should be returned till you know what your whole situation is. Other ways to control the crappeie: Possibly netting or trapping? This might also let you see waht else you have in there.
You may also want to wait another year or two to see if the water is always going down. How deep is it normally and what is it when its low? This low cycle may kill off fish and needs to be adressed if thats the case.
Feeders are always a good thing, but do you want to feed stuff if you kill it off anyway? There are many good threads on hear about feeder recommendations. Two are often refered to, Moultrie and Texas hunter. Each have their place. Try to find those threads.
You will want to start keeping records of ALL fish caught. There are charts on this website that will tell you if your fish are growing well or not. Keep track of weight and length of each and every fish, and probably the date you caught them. This way you will know if the fish are getting healthier. You could also set a small minnow trap or simialr, and see what small fish are present too.
