Here´s my translation. Comments, suggestions, alternative renderings highlighted, queries underlined.

Kveðja

Alan

Og enn mælti Gestur: "Sá var draumur þinn annar að þú þóttist hafa
And still Gestr spoke: „That-one was your second dream that you bethought-yourself to have

silfurhring á hendi. Þar muntu vera gift öðrum manni ágætum. Þeim muntu unna
a silver-ring on (your) arm/hand. There (ie this means) you-will be given-in-marriage to a second (given the listing of husbands that occurs, better suits the context, I think) excellent man. That-one (ie him) you-will love

mikið og njóta skamma stund. Kemur mér ekki það að óvörum þótt þú missir
greatly and (but) enjoy (him) for (only) a short time. That comes not upon me unawares (ie I am not surprised) even though you should-lose

hans með drukknun og eigi geri eg þann draum lengra. Sá var hinn þriðji draumur þinn
him by a death-by-drowning and I judge not that dream further (ie I make nothing more of it). That-one was your third dream

að þú þóttist hafa gullhring á hendi. Þar muntu eiga hinn
that you bethought-yourself to have a gold-ring on (your) arm/hand. There (ie this means) you-will (munt + þú, 2nd pers sg, indic.) have (marry) that

þriðja bónda. Ekki mun sá því meira verður sem þér þótti sá málmurinn
third husband. That-one (ie he, sá, nominative) will not (be) more worthy to that (extent) (því)  as (sem) that metal seemed to you

torugætari og dýrri en nær er það mínu hugboði að í það mund muni orðið
rarer and more-precious (ie than silver), but near is that to my fancy (ie I have a feeling) that at that time (mund, noun) (there) will happen

siðaskipti og muni sá þinn bóndi hafa tekið við þeim sið er vér hyggjum að
a change-of-faith and that-one, your husband, will (subjunctive)have accepted that faith which we think that

miklu sé betri og háleitari. En þar er þér þótti hringurinn í sundur stökkva,
were much the better and loftier. But there when the-ring seemed to you to spring asunder.,

nokkuð af þinni vangeymslu, og sást blóð koma úr hlutunum, þá mun
somewhat (nökkurr, Z2) from your negligence, and (you) saw blood come out-of the-parts, then will

sá þinn bóndi vera veginn. Muntu þá þykjast glöggst sjá þá þverbresti er
that-one (pronoun, nominative), your husband, be slain. You-will then bethink-yourself most-clearly (superl of glöggr) to see those cross-cracks (ie flaws, acc plural of -brestr) which

á þeim ráðahag hafa verið."
have been in that marriage (I presume this must be the dative sg form?).“

Og enn mælti Gestur: "Sjá er hinn fjórði draumur þinn að þú þóttist hafa
And still Gestr spoke: „This-one is your fourth dream, that you bethought-yourself to have

hjálm á höfði af gulli og settan gimsteinum og varð þér þungbær. Þar munt þú
a helmet on (your) head of gold and set with gemstones and (it) became for you heavy-to-bear. There (ie this means) you will (see above)

eiga hinn fjórða bónda. Sá mun vera mestur höfðingi og mun bera heldur
have that fourth husband. That-one (ie he) will be (the) greatest chieftain and will rather (more) bear

ægishjálm yfir þér. Og þar er þér þótti hann steypast út á Hvammsfjörð þá
a helmet-of-terror over you. And there when it seemed to you (note: dative)to tumble out into Hvammsfjörðr, then

mun hann þann sama fjörð hitta á efstum stundum síns lífs. Geri eg nú þenna
he will hit upon (visit) that same fjord (this is actually the direct object of hitta á) in (the) last-hours (stund, Z4) of his life. I judge now this

draum ekki lengra."
dream not further.“

Guðrúnu setti dreyrrauða meðan draumarnir voru ráðnir en engi hafði hún orð
Blood-red settled in Guðrún (ie Guðrún turned bright scarlet) while the dreams were interpreted but she had no words (ie she didn´t speak)

um fyrr en Gestur lauk sínu máli.
about (it) before (see fyrr, Z1) Gestr concluded his speech.

Þá segir Guðrún: "Hitta mundir þú fegri spár í þessu máli ef svo væri
Then Guðrún says: „You would (past subjunctive of munu) hit upon fairer prophecies in this matter/speaking if such (prophesies) were

í hendur þér búið af mér en haf þó þökk fyrir er þú hefir ráðið draumana. En
present (ie existed, see búa, Z7) in your hand (ie were available to you) from me (ie if they were in the dreams) but nevertheless have (imperative ie accept my) thanks for (it) that you have interpreted the-dreams. But

mikið er til að hyggja ef þetta allt skal eftir ganga."
much (of import) is to look-forward-to (or to ponder?) if all this shall go after (prove true, be fulfilled).“

Guðrún bauð þá Gesti af nýju að hann skyldi þar dveljast um daginn, kvað þá
Guðrún bade then Gestr anew that he should there stay during the-day, declared then

Ósvífur margt spaklegt tala mundu.
Ósvífr would speak very wisely.

Hann svarar: "Ríða mun eg sem eg hefi á kveðið en segja skaltu föður þínum
He answers: „I will ride as I have declared but you-shall say to your father

kveðju mína og seg honum þau mín orð að koma mun þar að skemmra mun í milli
my greetings and say to him those my words (neut acc pl) that a considerably (see munr, Z3) shorter (distance) will come about (koma at, Z4) between

bústaða okkarra Ósvífurs og mun okkur þá hægt um tal ef okkur er þá leyft að
our abodes, Ósvífr‘s (and mine), and (it) will then (be) easy concerning conversation if (it) is then permitted to us

talast við."
to speak with one-another.“