Not sure about the maps and the crosses but you are right about the spanish coins. Found this reference for your reference:-
"Pieces of eight were actually Spanish silver eight "reales" coins. The gold coins were called "escudos." These had the Spanish coat of arms on one side and two columns depicting the Pillars of Hercules (symbolizing the Straits of Gibraltar) on the other. It is thought that the twin pillars became such a recognized symbol for money that the modern dollar sign evolved from it.
The doubloon was a gold eight escudo coin--the highest value coin in the Spanish system. It had the a bust of the King of Spain's on one side and the Spanish coat of arms on the other. A handful of doubloons would have been a real treasure to any pirate. "