I see I have a bit of a backlog again. Here are some notes on the last
few installments.

> og skal nú yfir lúka með oss og eigi frá ganga fyrr en þeir eru

allir dauðir (who is the grammatical subject here?)

There is no explicit subject. We have to look at the context for the
implied subject "we". `ganga' is subordinated to `skal' which can be
used in an impersonal way, even though a fairly definite implied
subject may be intended. I can't think of a good matching example off
the top of my head, but here are a couple that cover part of the range
of usage; the first is very general "as a rule, one should", while the
second is more like "we ought to do this now" or "this is what must
now be done".

(1) Gáttir allar áður gangi fram um skoðast skyli
"All doorways should be scrutinised before one walks forward (through
them)."

(2) skal skjótliga um skör búa
"Let my hair be quickly prepared."

> Hann hafði haft sverð brugðið undir hendi sér og hjó til manns og

kom í skjöldinn og af sporðinn og fótinn af manninum. Þá kom Flosi að
og hjó á hálsinn Helga svo að þegar tók af höfuðið.

"He had had a sword drawn under his arm and hewed at a man and [the
blow] landed in his shield and [hewed] off the tip from his shield,
and the leg from the man. Then Flosi came and struck Helgi upon the
neck so that his head was severed instantly."

I think `hjó' is to be understood in the first sentence, perhaps
omitted for stylistic reasons to avoid repetition. A similar example
from Gísla saga: `Gísli hjó í móti með höggspjóti og af sporðinn
skildinum og af honum fótinn'. Regarding the second sentance, the
note in Gordon & Taylor says: "`tók' is impers[onal], equivalent to a
passive: `so that the head flew off.'" See Zoega `taka' "(11) impers.
it is taken; þá tók af veðrit (acc.) then the storm abated; kom á
fótinn, svá at af tók, the stroke came on his leg, so that it was cut
off; sýnina tekr frá e-m, one becomes blind; tók út skip Þangbrands,
Th.'s ship drifted out; um várit er sumarhita tók, when the summer
heat set in;".

> og mæltu það síðast svo að menn heyrðu.

I.e. "and those were the last words anyone heard them speak."

> oss munu öll vopnaskipti þungt ganga við þá

"all exchange of weapons with them will go hard/badly for us". That
is to say: "we'll get the worst of any exchange of weapons with them".

> og mun eg beina að mér þér

I think `mér' must be a typo for `með'. Gordon & Taylor: `ok mun ek
beina at með þér'. (Zoega: `beina at' or `til með e-m', to lend one
help, to assist one).

> með reykinum
> in-amongst (into the midtst of, see með, Z6) the smoke.

Or Zoega (8), "along" – following the path of the smoke (to hide
himself from view).

> Þá reið (ríða) að honum brúnásinn (brúnáss=ridge-pole, nom modern

spelling?)

Yes. Compare the edition of Konráð Gíslason and Eiríkur Jónsson: `þá
reið at hánum brúnássinn'.

> hlærð þú [...] þú vóst

Two more modernisms due to the adapted text we're using. In Old
Icelandic, these would be: `hlær þú' and `þú vátt'.