My sources don't have much to contribute to "Palooka." All Webster's unabridged says about its origin is "?". Slang and Euphemism Dictionary, Richard Spears, says:

palooka (also paluka) an oaf; an unskilled prizefighter, the name of a comic-strip prizefighter, "Joe Palooka." [U.S. slang, 1900s]