As long as I'm in the neighborhood with an earlier question,  can
someone answer a few quick newbie questions for me? 

It seems like every time I hear about SETI in the news they talk about
searching for a signal in specific "clear" wavelengths.   While this
makes sense in terms of picking up a clear signal it makes me
wonder... 

If the SETI equipment was pointed at the earth from out in space
would it detect signs of intelligence or would it be looking on all
the wrong wavelengths?   If it would detect a signal, from
approximately how many light-years could it detect it?  

Also as our airwaves become more crowded we are using better and
better compression to maximize signal density.  If we take that to
extreme, how good of a compression/encryption would need to be on a
signal before it would just look like white noise to the SETI
detectors?  Is there a way to test for this? 


Thanks for any input.