hear is hertz link-
http://www.hertzaudiovideo.com/default_en.htm
yes there are audio shop that great work, but you pay for what you get.
If you have the money to let them do what you can do for free, them have them do it.
yes when you hook up your front amp it's just like hooking up your sub amp.
if the amp has LP-HP filters you'll need to set them up right so you wont blow your speakers.
but make sure even if you have a shop set your amp gains low, I mean turn your gains on your amp all the way down, then turn your volume on your head unit about 75% UP, then you can turn your gains slowly up maybe around 1/3 which should give you enough volume that will be clean without much distortion.
make sure your HP is off, you can xover your head unit @ 80hz.
this is a start, as you start to play more with your gear it will be easier in time.
before you change out your battery look into the BIG THREE, you can google pic on the web to see how others have done it. it's really easy to do.
to bad you did live in northern california i would help you out.