Please overlook this question if previously asked. Is there any already made (free or purchase) poses of Japanese formal and informal bows both standing and knelling? If not, are there any reference images of such poses?

I don't know about poses (try the RMP for martial arts poses), but references (as can be deduced) can be found in martial arts references. Japanese martial arts (aikido, jujutsu, karate) always start out with the politenesses - bowing, kneeling, sitting, bowing while kneeling. In the martial arts, these are called 'Rei' or 'Rei-hou' (etiquette). Standing bow - shizen rei Sitting bow - seiza rei Open Sitting bow - fudo za rei Half-kneeling bow before fight - jinchu rei

There are some Geisha Poses at Poser Pros. I can't recall off hand who put them out... but if you look up "Geisha" you should find it.