Chloe is Cl-oh-ee. I hear people say just cl-oh a lot...
Chie is Chee-yay
Zylle is Z-ill (like pill) Althouh someone called her z-eye-lee once and it sounded cool.
Alielle is Ally-el

Walnut, Jess, Speed Racer, and Chubby are all pretty self-explanatory.