A coqui is a frog found in Puerto
Rico. It's named for the sound it makes! I seems like a nickname that would originate not in relation to the name, but to the person. Link:
http://en.wikipedia.org/wiki/Coqui
No idea about the others!
Julia Keelan
"I don't mean to be rude-" he began in a tone that threatened rudeness in every syllable.
"-yet, sadly, accidental rudeness occurs alarmingly often."
~ From Harry Potter and The Half Blood Prince by J.K. Rowling. Vernon Dursley to Albus Dumbledore.