What should a bilingual site look like from the backend?

Question

Suddenly I have lost track on my new build D7 German/English site. Nothing I attempt seems to work. I will tell more about the problems below but I think its hard to help me there as long as I am not sure if the base is correct. So, my concrete question is:

How should the mainmenu of a bilingual D7 site look like, i.e. is there only one main menu and the translations of the links can just be seen after clicking on them?

Home
About Us
-Team
-Jobs

Or should there be a menu tree for German and another one for English?

Home
About Us
-Team
-Jobs
Start
Über uns
-Mitarbeiter
-Karriere

(Both is possible and I am still strugelling to understand if this is a bug or a feature. See Why are there so many different ways to translate menus?)

Well, here are some of the problems I thought I overcome and which now seem to be everywhere on my site:

1. Sometimes, a translated site appears as an item on its own in content list, sometimes the translation seems to be stores in the main language item.
2. On some pages I may not click on English although there exists a translated version of the site although it should be linked as far as I see.
3. If a link works, the bread crump path differs from the real path:

German:

Start / Über uns / Karriere

English:

Home / Jobs

Answer 1

I figured out that a correct localized main menu should be bilingual or multilingual and therefore look like this:

Home About Us -Team -Jobs Start Über uns -Mitarbeiter -Karriere Infographic (EN: Infographic, DE: Infografik)

The possibility to save localizations inside of the node (my possibiliy 1 in the question) are for pages that are not necessary to translate (e.g. they show only a infographic, as in my example above) but the links pointing to them.

Hope this helps other people with this question.