Here’s my translation

Alan

Hann var slyppr ok fór leikandi sem aðrir, þar til er hann kom fyrir konung. 
He was unarmed and went (ie started) dancing like (the) others, until he came before (the) king.

Hann reiðir þá upp hnefann ok dregr svá snöggt um nasir konungi, at ór honum hrutu þrjár tennrnar, en blóð stökk ór nösum hans ok munni, en hann fell sjálfr í öngvit.
He then brandishes up (his) the-fist and draws (swipes) (it) so suddenly across (the) nostrils of (the) king, that three teeth flew out of him (ie the king), and blood spurted out of his nostrils and mouth, but (and) he himself fell into a fainting-fit.

Sigurðr sér nú þetta. 
Sigurðr now sees this.

Hann kastar nú hörpunni upp í sængina, en rak báða hnefana í millum herða kvámumanninum, en hann sneri undan, en Sigurðr eftir honum ok þeir Siggeirr ok allir aðrir, en sumir styrmdu yfir konunginum. 
He casts now the-harp up into the-bed, but (and) drove both fists between (the) shoulders of the-recent-arrival (stranger, lit: the-person-of-arrival, kvámumaðr, CV), but (and) he retreats (flees, lit: turns away), but (and) Sigurðr (goes) after him and-also they, Siggeirr and all (the) others, but some (folk) crowded-around the (wounded) king.

Smiðr tók í hönd brúðinni ok leiddi hana upp í sængina ok læsti hana innan í maga hörpunnar, en þeir drógu hana út um glugginn, sem úti váru, ok svá Smið með, ok flýttu sér til skips ok gengu síðan út á þat. 
Smiðr extended (his) hand to the-bride and led her up into the-bed and locked her from-within (it reads to me a bit like, perhaps, Smiðr has locked himself inside the harp as well) in (the) belly of the-harp, and those who were outside drew her out through the-window, and also Smiðr with (her) (perhaps, because he was inside the harp also), and made-haste (sped themselves, flýta) to (the) ship and went (on foot) after-that out on to that (ie boarded it).

Þá var sá þar kominn, er konunginn hafði slegit. 
Then (ie by that time) that-one (ie he) who had struck the king (accusative) was (had) come there.

Sigurðr gekk ok út á skipit, er hann kom at, en Siggeirr eftir honum með brugðit sverð. 
Sigurðr also went (on foot) out onto (ie aboard) the-ship, when he came to (it), but (and) Siggeirr (went) after him with (his) sword drawn (pp of bregða, Z1)

Sigurðr snýr þá aftr í móti honum ok hratt honum á kaf; urðu hans menn at draga hann á land verr en dauðan. 
Sigurðr turns now back towards him and thrust him under water; his folk (men) were-forced to pull him on to land (ashore) worse than dead.

En Smiðr hjó landfestina, ok drógu menn segl upp ok gerðu bæði at sigla ok róa ok létu ganga út á haf slíkt er mátti. 
But (And) Smiðr (has Smiðr got out of the harp or was he never inside it?) cut (the) moorings, and folk (men) drew up (the) sail(s) and did (göra as auxiliary verb, Z11) both sail and row and caused (the ship) to go out to sea in-such-wise as (they) could (ie by whatever means available to them.)

Hrærekr hljóp til skips ok margir menn aðrir með honum, en er skipum var fram hrundit, fell þar inn kolblár sjór, ok urðu þeir at landi at leggja ok urðu at hafa sitt hugarmót svá búit, váru ok allir menn verr en ráðlausir af drykkjuskap.
Hrærekr ran towards (the) ship and many other folk (men) with him, but when (it) was thrust forward with the ships (plural) (ie when they set their ships in motion), (the) coal-black sea flowed there-in (Remember: Herrauðr lætr menn sína meiða öll þau skip), and they were-forced (back) onto land (leggja at landi, Z14) and were-forced to have their meeting-of-mind/heart (pep-talk, brainstorming session?) thus, also all folk (men) were worse than useless from (the) hard-drinking.

Konungr raknar nú við ok var þó lítils máttar, ok leituðu menn við at næra hann, en hann var mjök máttdreginn. 
(The) king now recovered-his-senses and was nevertheless of little-strength, and folk (men) tried to invigorate him, but he was very weak (drained of strength)

Snerist nú veizlan í sút ok sorg. 
The-banquet now turns-itself into grief and sorrow.

En þá konungr hresstist, gerðu þeir ráð sín, ok kom þeim þat saman at slíta eigi fjölmenninu ok búast sem skjótast at fara eftir þeim fóstbræðrum.
But (And) when (the) king recovered-his-strength, they made their plans, and that came together for them (ie they came to an agreement) to not split the-crowd-of-people (“break up-the-band”) and to-ready-themselves as-swiftly-as-possible to go after those foster-brothers.