Ho stands for "hole" and the joke was:
Wong Ho = Wrong Hole
Wie Ho = Right Hole
Ash Ho = AssHole
And Wang didn't have much thought about it, but it could be just Wang in the sense of penis as you said, meaning he's a dick.
I think official sources (if not Jab himself) confirmed the "hole" puns being the source of their names.
Regardless, the Ho family is supposed to be Chinese (puns aside, the names do sound Chinese), so the whole Samurai thing makes no sense (unless Jab solves it by making Wie Japanese and giving her a Japanese-sounding nubile name.
PS:
I fixed Ash, the AI colored giving her a full mouth of teeth when her front teeth are missing.
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