Comb is small and pale, with no wattle development, so I think you are safe with Houdini being a pullet. I think the name Houdini is fine for a female, too.
Dot, Hei Hei and Houdini are pullets.
Fritto and Zippy are cockerels.
Vaiana is questionable but I lean to it being a cockerel.
How old are these younguns?