Avic-z110bt w/ stock amp + speakers

[Marceltj4.6is]

Hi all,
I've searched all over for the answer to this question and can't seem to come up with any specific details on how to implement.

I want to install my beautiful new AVIC head unit but don't want to really mess with anything else at the moment.

Here's what I've been able to gather thus far.

1) get a harness
2) use harness at radio in trunck - is there a harness for the front? Or do I need to tap into wires?
3) since the tuner is unplugged at this point, how and where do tap into the amp?
4) Do I need to run an antenna extension cable to the front of the car for the new unit?

Many thanks!!