Will it work with Unity 4.7.2/ NGUI 3.6.8?

Is there a version of I2 Localization I can get that is compatible with these versions of Unity/ NGUI?

The latest version (2.6.6) is compatible. I just released to 5.0.0 in the AssetStore as 4.x is used by less than 5% of the unity users and it was annoying having to prepare and submit every alpha/release in each unity version.

But if you download the plugin in a 5.0 unity, you will be able to use that package in 4.7.
Alternatively, if you send me an Invoice Number I can give you access to the Beta Folder and you can download the newest packages from there without having to install Unity 5.

Is there some tool to automatically create an initial CSV file, and add localization components, from my existing labels?

There is a tool that ports NGUI localization to I2L. But it only do so, for localized NGUI projects (i.e. those with UILocalize components).
Most of the time you don't want every single label to be localized, given that lot of them will only show stats, numbers, etc.

However, is really easy to port (I could send you a version of the tool that detect UILabel instead of UILocalize)

or even easier if you just want to localize everything:

- Open your scene
- drag all your prefabs into the scene
- type UILabel in the search box, (that will show all gameobjects using that component)
- click "Add Component" and add a Localize component to all

By adding a Localize component, the plugin will "infer" the term by using the label text.

So, if you then open the Assets \ I2 \ Resources \ I2Languages.prefab, ALL of the inferred terms will be shown. you just need to click "Select Missing Terms" and then "Add Terms". That will create a Term for every text you have in your game.

And finally, go to the Languages tab, and add the languages you want.
Click "Translate ALL" and it will translate each text to every language.

Easy! Localization....done!
Hope that helps,
Frank