The Spanish did come to Ireland during the age of discovery, but the phoenicians probably came there as early as 1000 BC
The "Black irish" refers to their hair and eye color not the color of their skin
As for Jews, remember that they were kicked out of their homelands around 200 AD after they had slaughtered thousands of gentiles in the Bar Kochkba revolt. And genetically Jews in Europe are Jewish on the male line and Southern European on the female line - meaning that the Jewish males intermarried with locals. This has no impact on who is jewish or not as the entire "descended from your mother" is a later condition.
Many Jews converted, many half-Jews would spread. Over 2000 years you can expect the genes to be widely dispersed.
In 1588 the destruction of the Spanish Armada off the west coast of Ireland (mostly by Atlantic storms) put a lot of survivors ashore, and many simply became part of the population, since you couldn't pick up a ride home very easily.