Wow!
Lots of questions. I can't help you with the radar stuff but Garmin makes a
neat little unit for $999.00 at West marine. It interfaces with most NEMA
electronics.
In Baja it might have been whales but I wouldn't know.

I sail on lake Erie and the Garmin 72 works well for me.($154.95 at wallmarts)
It comes with all the coast guard placed buoys mapped out. Accurate to 15 feet.

Good luck,
John