Differing Key layouts

[Stolid]

I'm once again in a conundrum: I'm looking at the US purchase page and am only given the choices of Western spanish and US English. I do a bit of work in Japanese, though, and was wondering if a Japanese keyboard setup would be preferable. I'm coming at this from a PC standpoint (on Japanese keyboards I've seen, an extra key is on the keyboard to switch between the hiragana, katakana, and roman characters) -- if the Mac has this same functionality than I'd definatly prefer a keyboard with that extra key on it in some way/shape/form. I have a headache in Windows every time I do some Japanese on my laptop because I have to use the mouse to change between these modes (you can do some keybinding to get around it; but I'd much rather a 'real' dedicated key)
So I was wondering if anyone here knew:
A.) How Japanese keyboards on Macs are arranged, preferably with pictures. Specific focus on the layout of PowerBook keyboards.
B.) If there were any reasonable (as in not buying from apple.co.jp) way to get the extra key to switch modes; assuming this is the Mac's setup. Reference the PowerBook above; I'd rather not lug an external keyboard around.

[bousozoku]

I was trying to remember the last time I saw a Japanese Apple keyboard. According to the Apple website, it uses JIS layout. However, many people just use the Kotoeri input method and type Romaji instead. From various posts I've read over the past two years, there don't seem to be that many people using kana input.

I would guess that there is a kana key on one side (left?) of the space bar.

I've seen the keyboards on various historical websites but can't think of one right now and Kodawarisan is down at the moment.

[Doraemon]

If you're using the English OS X, a Japanese keyboard won't help you at all since the input of Japanese characters is via Roman letters.

[MoparShaha]

I'd just use the standard English layout, and use the Kotoeri input system OS X uses, like bousozoku said. It's actually pretty quick once you get the hang of it. When you're typing in Hiragana, you just hold down the shift key to type in Katagana. And when you want something in Kanji, you just kit the return key after the word, and it automatically turns it into Kanji for you.

[Stolid]

Shift for Katakana? Interesting system. Does Capslock work as I'd expect then (lock in Katakana mode)? Is there a quick way to 'go roman' without the mouse? If both of those are true I'd be quite happy with the setup.

[MoparShaha]

Caps lock while in Hiragana does not lock in Katakana. You need to switch to Katakana mode. You can use key combinations to switch from Japanese to Roman input though. See the attached image. It's a shot of the language input menu.

[bousozoku]

You can change the language with Command-spacebar but you can also use option-tab to cycle through Japanese.

Normally, I'm typing hiragana and if I need katakana, I use option-tab to change it. The space bar brings up the most frequent kanji choice for a certain combination of kana. Pressing the space bar against brings up a list of choices.

Most things can be entered using Hepburn-shiki unaltered.