Marine Radio install question

Hey All,

I'm about to install a Jensen stereo (Model MSR2007) in my Robalo.
There is a blue wire coming out of the radio's harness that is marked
"Power Antenna".  Any idea what that should be connected to?  It is
not the Antenna connection which is a whole seperate connector on the
other side of the radio.

Also, there is no mention of connecting any wire from the radio
directly to the battery for a continious power source.  The main lead
(red wire) is supposed to be connected to +12 switched.  The old radio
(that I removed) had a wire connected directly to the battery with a
small plastic fuse casing in the middle.  Do modern radios use a
different method to maintain memory when the power is switched off?

Any thoughts would be appreciated.
Thanks,
Rob