2. US PSX
3. There is no way to do that right now (and probably ever). I made an excel sheet that generates bytes for a single character, but that's all it does so I haven't release it to the public. You can use stuff like Tile Molester I guess, but personally I hate that program and can't really help on that because I'm not all that familiar with it... I THINK it has export/import functions though.
4. Event Script? If you mean changing the font colour, or changing the printing speed, or adding selectable options, then yes, otherwise I don't know what you mean.
5. I've googled before and there are websites with a ton of the game's text in Japanese. Even if you can't get the Japanese text through tactext, it would be a good start. And yes, there is a font width table for the Japanese version; even if there's only 2 out of 2200 characters that have a width different than 10px (0x0A). If you hex search for a lot of 0x0A in a row, you should find it easily enough.
You might cry and abandon your project because of Tactext. I'm not sure if the best version for it works that flawlessly, but I've heard plenty of horror stories... Spending hours and hours trying to make it work, and still no go.
If you're going to use Tactext, you should really use my FFTText Editor as well: http://ffhacktics.com/smf/index.php?topic=11204
...if that would even work with a .ffttext generated from the WotL version; I don't know.
Either way, you'll have to figure a lot of things on your own. That's what we have. Just about no one here hacks WotL because we just think it's an inferior version. If you insist on using it, well, good luck to you.