Härlig är jorden 

This is an old psalm. The song livgardet reused the same melodic motive

This tune is mostly played in funerals in sweden and finland, it sings about how beautiful the Earth and Heaven is. It's not a question of if, but when, someone hears this in Sweden, at least if they get a "swedish" traditional funeral. So yes, they probably subconciously or conciously chose this melody as a base. It's simple yet *extremely* powerful.

Yes it does. I think they also said, that Livgardet and the Royal Guard are based off hymns that they played back in Sweden