"Plane crash"

Are you sure it's "Frugelandeter" and not "Flugelandeter"? "Fliegen" is German for "to fly" and the "ie" often becomes "u" when conjugated, so that would make more sense. Alternatively, perhaps it's a form of "früh", meaning "early" (I suppose you could call a crash an "early" landing, though it seems very idiomatic). Jens is almost certainly right it's not German; the "ge" is characteristic of German past tense, but throwing in the "et" makes it look like the bastard child of German and Norwegian past tense, so Dutch makes as much sense as anything.

"On the Swedish border at/toward/by the [...] glacier".

The Nordic tendency toward compound words makes it hard to tell what's on the front of "glacier"; your guess is as good as and probably far better than mine on WHICH glacier. "Nach" is one of those annoying prepositions that can have various meaning depending on context, but "overlooking" probably fits best here.

"Mass grave: Where? This is a soldiers cemetery with fallen soldiers reburied in coffins. Narvik, Trondheim? One can see the flag with the German Iron Cross. Salvaged from a torpedo boat? Life boat?"

"uss" is probably "ist", the German equivalent of "ist"; that makes the sentence a lot more logical. Are you sure "gefallensargen" is one word? A lot depends on that; if it IS one word it could also be read as "This is a soldiers cemetery with soldiers reburied. Fallen coffins. Narvik, Trondheim?" Unless it looks there are fallen coffins in the picture, however, it probably says they found a mass soldiers grave, put them in coffins and reburied them in a proper cemetery. The German for "life boat" is apparently "Rettungsboot", so maybe that somehow morphed into "Roganbotn".

This may give you an "Engrish" result, but I fed the text into dicios (edited based on the above guesswork and the contributions from Jens and kHz) for English and then Norwegian translation (apparently they don't allow direct German to Norwegian; schade ) and got this:

Krech landet/Frugelandeter

På svenskegrensen utsikt giccekokkagletscher

Massegrav: Hvor? Dette er en kirkegård å bli begravet med soldater falt kister, Narvik, Trondheim? Du kan se flagget med Deutche eiseren korset. Reddet fra en torpedo båt? redningsskøyte?