Hi everyone,
I've recently trying to understand FIR ad IIR filters.  I think I have got it pretty much under my hat, but I just want to make certain of a few things.

(1) What exactly is the difference between impulse response and frequency response? 
(2) Is the equation for calculating coefficients only needed to create Fc other than SR/4?

Well Thanks for your time.  I really appreciate it.  Teaching yourself some of this stuff can be quite frustrating sometimes. 

Mark