A car audio shop should be able to handle installing this for you.
Make sure you tell them -exactly- what you want, and make sure they do it.
Here's what you should probably be asking for:
-Dedicated power feed from battery.
-Fuse installed -AT- the battery, or within a few inches.
-Positive lead should go to positive post on battery, or factory installed accessory power point.
-Negative lead grounded to vehicle body.
-All wiring in split loom.
-Any and all penetrations through metal body must have proper sized grommet installed, this includes penetrations through fire wall.
Do not let them install wiring to fuse box, use fuse taps, or tap into -ANY- existing vehicle wiring. Don't let them BS you into accepting that. That includes tapping into cigarette lighter power feed.
Be specific about what you want and make sure they do it. All wiring should be neatly run and secured properly.
I've seen some audio shops do a good job, and I've seen some do total crap installs. If you know what it should look like, and you watch them closely, you should be OK. Talk to them about exactly what you want before letting them touch your car. Do not pay them until the work is done to your satisfaction.
Also:
what are you doing about an antenna?