Re: Where's the hara?
In answer to the question rather prosaically, in Japanese the hara is the abdomen, stomach, guts, belly. The tanden is by no means a well-known concept over here. People sometimes know where it is, but there are no vernacular expressions, and outside of the healing arts, some Chinese and Indian arts it's not bandied about much. According to varoous sources it's about two or three fingers' width below and behind the navel.
The Japanese have a few expressions regarding the hara that may be useful.
腹が立ってる hara ga tatteru: get angry, exasperated
腹が減って軍ができぬ hara ga hette ikusa ga dekinu: you can't do anything on an empty stomach (lit: an army can't do anything on an empty stomach... don't know if this comes from the western expression or not, but I suspect something way older, maybe Sun Tzu but I haven't checked).
腹は決った hara ha(wa) kimetta: made your mind up.
This post's getting too long, so I'll leave you with 小説は腹の足しにはならない。。。 shousetsu ha hara no tashi ni ha naranai: you can't eat a novel!