Quote Originally Posted by fluter View Post
Does this mean the almost, but not quite silent English "ah(r)", or some kind of Continental trilled 'r'? "yeah" versus "yerrr"
Not trilled. More like the not quite silent English "ah(r)".

Where's Icelandic fit amongst the three, being closer to Old Norse?
I'd say more in the middle of the mouth. Many times, "s" has an almost "sh" sound - not quite, and that's more a mid-mouth kind of sound. As in Jonasson, which would be more like Jonass(h)on. And "fl" in Icelandic is pronounced "bl", so the airport Keflavik is pronounced KEB' la veek (which again, is more a midmouth kind of sound that Keflavik (with an "f') would be. And most words have a stress on the first syllable - so an American's inclination to pronounced the airport Kuh FLAH vik is doubly wrong.

Icelandic is a very complicated language, but the pronunciation rules (while not entirely intuitive) are very regularly applied.