Laoise,
I do not know whether they are actually singing all of these songs, but this mixture of English, German, Pop, and Folk, old and young gives you in general a good idea of their singing. We are exposed (radio) to about 50% English music, 40 % German, and 10% French, Italian, and Spanish. So English is eagerly accepted as a language for singing, whether you understand the words or not.
When I was a boy scout, we nearly exclusively sang songs in German language though several of them were translated from other languages. Little we cared about folk or pop origin. But when we first went abroad (Scotland) our scoutmaster insisted we learned songs in English as well (in case we were asked to sing; we were, of course, but people prefered us singing in German). So I learned "Should old acquaintance..." and "Loch Lomond" without understanding the words then.
Later on we enjoyed singing everything which could be considered raunchy, or in any respect objectionable. So we thought it fun to sing "God shave the queen" or "We make Ian Paisley join the IRA" in the streets of Belfast.
In my experience, the love of singing just anything comes first, and the real understanding of the lyrics and the developing of a taste for the music comes later. But of course a parent or educator can influence that taste. And I'm doing the best I can with my baby daughter.

Wolfgang