Custom Fields (and I18N)

[azeroth2b]

Is there any way to get a field from a different page?
Like get_custom_field($name, Page-SlugXY)

No, there isn't (mainly to keep it fast and simple).
What do you want to achieve?

Since the data for the custom field is stored with the page, you can access using getPageContent($Slug, $Content) where slug is the slug and content is any field stored in the XML file. I think this is a frowned upon practice for a few reasons, but it does work.