[Shrocat]

Get a Digital Voltmeter, go to radio shack, not too expensive. This will help you immensely. And get a test light, with aligator clips.
I don't see what year it is, but the trouble shooting will
be generic. Try to find some type of manual on the car.
Go to a library and look for one. Or use the library to access All Data for information.
Once you have some wiring diagrams, you can start looking for the problems. Start with the current drain on the battery. Disconnect the negative side of the battery and then connect the test light between the cable and the battery. The light will probably glow brightly, because of the short. Then start pulling fuses, and check the light after each fuse is pulled. When the light gets very dim, you have found the circuit with the problem. From there it is a simple matter of just tracing wires and finding bad spots or components.
If the problem doesnt' go away by pulling the fuses, then you need to look at the wiring between the battery and the fuse box. Also there will be wires and components that do not go to the fuse box. This is one reason why you need the wiring diagram.
As far as the fans go, one comes on when the engine warms up, the other when the AC comes on. I would guess that the main fan is the one blowing the fuse. It is controlled through a temperature sensor, check the sensor, it may be bad. And follow the wiring from the fuse, there is probably something shorted there.
And do not assume that the car is wired properly, without a diagram. Since there are so many seemingly unrelated problems, I bet the owner screwed things up himself.
But, once you get the car straightened out, you will realize that you did not get ripped off. A grand for a park avenue with 140K is not very much.
And now you know, never buy a car with any problems that you do not know how to fix. No matter what the owner tells you about the problem, you need to find out on your own. So take it to a mechanic before buying.