Problems with default language

When setting default language (in translation tool) to something different than English:

1- I can select more than 1 default language, or no default language. I think there should be one and only one default language.

2- All applications are written with templates in English. But if default language isn't English, I cannot translate strings to the default language in translation tool. I think it should always consider applications as written in English, even when default language isn't English. The best would be to show ALL languages (including default language). This way, there even could be English to English translations, which could address the problem when to different concept use the same word in English. By putting a number or something else into the string in the template, it would allow to translate it correctly in other languages.