Question: Old Norse o-ogonek, and accented Danish characters

I just got through studying a couple of pages by Michael Everson (the
ones concerning the old thorn and yogh letters).  And I discovered in
Old Norse (and pre-modern Icelandic) not only the complex vowels æ (ae
ligature), ø (o-slash), and å (a-ring), but an 'o' with an ogonek
(reversed cedilla), which in Polish (and Old Lithuanian) to mark nasal
vowels.

So what exactly is the value of Old Norse/Icelandic O-ogonek?

Also, Unicode has within the Latin Extended B block (some very exotic
Latin modifications are used; they can be found in the Lucida Sans
Unicode every Windows 95/NT 4.0/98/2000 user should have.  But the
newest form of Times New Roman, Arial, Courier, and definitely other
popular fonts have the three aforementioned modern Danish vowels, æ ø å
(is that the correct order?), with acute accents.  Is that used to mark
a high tone or a stress accent?  Or does the acute accent mark a long
vowel, like Czech and Hungarian?

Kudos for your help,

Daniel A. Wier (call me Danny)
Lufkin, Texas USA
http://communities.msn.com/DaWier
MSN Messenger Service: dawier@hotmail.com
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