They are decently accurate for late era, non-soldier mercenaries in Japan anyway, so it's not as though that matters.
They were mostly Shinto for most of their history.b) Even arguing for historical accuracy, many Samurai were Buddhists, so perfecting oneself would be a realistic ideal for them. (Not to mention the romanticizing of Ronin and that whole approach to Samurai.)
PRC mashup of wild plains outrider, order of the bow initiate and cavalier is probably the best representation. Any class to get in would be fine.