Problems With Presonus Firestudio

I am having problems with compatability with my brand new Presonus Firestudio recording interface and Logic pro 8. I am new to logic but not to home recording, and i cant understand what might be the problem. When i use the firestudio with garageband it works easily. In the garageband sound preferences there are input AND output channels that the user can define. (i.e. you can set your input channels to come from the firestudio while the output channels go to the computer speakers or headphone jacks or whatever you define it as).
From what i have seen in logic, there is only one option for your audio settings. when in preferences and under audio, there is a "device" setting in which you can define your audio device. Wheather this is input AND output for the program, i do not know. but the problem i am experiencing is that whenever i choose the firepod as the input device, no sound from logic will play from the speakers whatsoever. My first thought was that maybe ouput was going straight to the firestudio, but after plugging headphones into it this also did not work. Has anyone had success getting their firestudio to work in logic? if so let me know what settings you had to use, and how you got to moniter your input from from the firestudio via your computer.

p.s.
another WIERD problem i have run into, is that if i shut off the firestudio while logic is open, alot of times it will shut down my whole computer. i have never heard of this happening. what am i doing wrong?

thanks!