Hi!
I have been creating a few effects (mostly distortion) from schematics and decided I would like to build my own circuit from scratch. I am currently in an electrical engineering program so i understand how transistors work, and I can design a basic amplifier (common emitter). Where I am having problems is with modifying the circuit for specific results. Here are some of my questions:

What are the parameters that I need to be designing my circuit around?
What effect does changing those parameters have?
Why use negative feedback vs. reducing input signal?
Am I looking for voltage gain or current gain or both?
What does input and output impedance mean? (I understand the concept of impedance but how does it apply to amplifiers?)
How can I calculate frequency response of a low or highpass filter? (again I am familiar with f=1/2piXC but how do I apply it?)

Thats a lot of ground to cover but any help would be appreciated.
Some of my questions may be odd because my knowledge is geared towards power & utilities but all answers are welcomed.