Hi Johannes

Firstly don't believe anything SDAI tells you too readily - none of us truly understand him so he'd probably confuse you too.

Secondly while the light from distant galaxies has travelled the Universe has expanded and hence the light has expanded too because the geodesics light follows have expanded with the Cosmos - that's the cause of the red-shift. Geodesics - if you're not sure about them - are the shortest paths between two points on a curved surface or in a curved space. They're the equivalent for curved space of straight lines in flat-space.

Read up on Cosmology from a good source. Prof Ned Wright's pages are an ideal introduction...

http://www.astro.ucla.edu/~wright/cosmo_01.htm

...read these carefully and many of your current questions will be answered.

Adam