There might be answers to some of your other puzzles in amongst this
lot [ http://tech.groups.yahoo.com/group/norse_course/message/9313 ].
If there's anything still baffling, let me know!

viðvörun = viðvaran "a warning"
verðr, adj. "worth, worthy"

viðvörunarvert, adj.n. "worth taking as a warning", i.e. "a
warning/example to others".