Where are you located?
You should not need the blue antena unless you have a powered antenna like a car (this is the wire that would tell the antenna to raise when the radio was turned on).
Their should be a red power wire, a black ground and a yellow fused wire.
The yellow wire should be connected to the power source along with the red. I connect them both to same because I do not care about station emory when power is off, etc. (altho my power is not ignition switch based).
As far as dual battery, I would get another battery, get a combiner like this
http://www.yandina.com/c100Info.htm for $50.
Depending on the fuse panel, etc on your boat ( I would add a fuse block if I were you in case you want to connect more. My wiring was screwey so I added a nice Blue Seas fuse block and am connecting all my stuff needing power to that going forward).
Anyway,so, witht his device, you connect each red lead to the + on your batteries. You will need to get a black ground cable to connect both battery - together. Connect the black ground to one of the - on one of the batteries (just 1). Connect the starter from your engine to the + on your starting battery. Connect your fuse block, fuse panel etc to your other battery + and their ground wires to that battery's -.
Now, what this device does is connects both batteries together when your engine is running. This allows both batteries to charge at the same time. When the engine is off, it disconnects the bateries from each other. So, if you have your radio, baitwell etc on all day and run the battery down, your starting battery will be fresh and fully charged (provided it is a healthy battery) because all of the devices will be drawn off of the house battery.
Nothing other then the starter should be connected to the starting battery.
Their is also a green wire you can conect to a switch that will allow you to manually connect the batteries (basically to jump) in case your starting battery is drawn down, but that should never happen if you have a healthy battery and only starter s connected to it,. but this works in an emergency. You can use on off switches etc with this, but I am not going to bother making it more complicated.
This is the exact same setup I will be installing in the spring for my boat.
If you are local to me or my boat in Keyport ( I live in North jersey tho), I can def give you a hand with the radio no problem. That and the battery stuff are one of the few things I can tackle myself.
I need help with all my other projects