Because it's my favorite poem! No, really, I like its rhythm, language and
"morals".
But that's not the only reason. Krákumál has the important characteristics
of skaldic
poetry without being quite as obscure as most of it is. Usually the
word-order is
understandable and the kennings are simple and well chosen.
Krákumál was a popular poem in the 19th century but has long since fallen
out of
fashion. It is the source of some interesting misconceptions about vikings
including the infamous drinking from skulls...
2. What is "grafvitnis morð"?
My answer:
That would be "the murder of the dig-wulf" with "dig-wulf" meaning serpent.
(I seem to remember you understanding "vitnir" in another way but that
shouldn't
change the meaning of "grafvitnir".) The "murder of the serpent" is then,
Ragnarr's
slaying of the ling-worm.