> ... og bað þau gera nokkurn hlut þann er Hrúti væri
> svívirðing að.

> ... and asked them (to) make no such participation that
> Hrut would be disgraced at.

> ... and asked them to take some part in that which to Hrut
> would be dishonor.

> ... and asked them to do some thing, that which would-be a
> disgrace to Hrútr.

Just for the record, this is <hlutr> (Z7) and <nökkurr>
'some'.

> En litlu síðar gera þau heimanferð sína Kotkell og Gríma
> og synir þeirra.

> But a little later they, Kotkell and Grima and their sons,
> make a journey from home.

> And a little later they, Kotkell and Grima and their sons,
> made their journey from home.

> But (And) a little later, they made a
> journey-from-their-home, Kotkell and Gríma and their sons.

Rob's right about the present tense.

> Þau fóru á bæ Hrúts og gerðu þar seið mikinn.

> They went to Hrut's farm and did (i.e., performed) much
> sorcery there.

> They went to Hrut’s farm and there made great magic.

> They journey to Hrútr‘s farmhouse (MM&HP have „on (the
> roof of his) farmhouse“) and made there a great
> incantation.

So far as I can tell, <á> in <fara á> + accus. could be
either 'to' or 'onto', so MM&HP could be relying on other
sources of information on how seiðr was normally(!) made.

> Kári sofnaði nær ekki því að til hans var leikur ger.

> Kari almost didn't fall asleep because to him a play
> sister was sent. (?)

> Kari did not sleep near because (the) attack was aimed at
> him.

> Kári did not not nearly (quite?) fall-asleep because (the)
> attack (here, the incantation) was made against (directed
> towards) him (see leikr er görr til e-s, under leikr, Z1).

I think that <ekki> here is used substantively in the sense
'nothing': 'Kári slept nearly nothing', meaning that he
hardly slept. Usage examples suggest that <sofna> 'to fall
asleep' also had senses approaching 'to be asleep'.

> Hann gekk á seiðinn og féll þegar dauður niður.

> He went to the spell and at once fell down dead.

> He fell victim to the magic and fell down dead at once.

> He walked into (possibly, submitted to, fell under?, cf
> ganga á vald e-s, under ganga Z15,) the-incantation
> (spell) and fell down dead at-once.

I'm inclined to go with the literal reading; <ganga á vald
e-s/e-m> strikes me as a fairly atypical idiom, so I'm not
inclined to extend it without very good reason (though I'll
admit that I'd not be astonished if it turned out that such
an extension was possible).

> Ólafur varð óður við þessi tíðindi og segir verið hafa
> mikla vanhyggju er þeir höfðu látið sitja slík illmenni
> hið næsta sér sem þau Kotkell voru, sagði og Þorleik hafa
> sér illan hlut af deilt af málum við Hrút en kvað þó meira
> að orðið en hann mundi vilja.

> Olaf became furious with this news and says has been much
> lack of forethought when they had sat such bad men as they
> the Kotkells were next to themselves, said also Thorleik
> has himself bad part of allotment of the case with Hrut
> and stated yet more to become than he would want.

> Olaf became furious at these tidings and says (it) to have
> been a great lack of foresight when they allowed such evil
> men, as they Kotkell (etc.) to settle the nearest to them,
> said also Thorleik to have dealt himself an evil part of
> the matter with Hrut and said still more to (have?)
> happened than he would want.

> Ólafr became mad (furious) at these tidings and says
> (there) to have been a great-lack-of-forethought that
> (when?) they had allowed such a wicked-persons to sit
> (stay) right-next to them as they, Kotkell (and family),
> were, said also Þorleikr to have dealt (deila) off for
> himself a bad lot (hlutr, Z1) (brought these troubles on
> himself?) from (his) dealings with Hrútr but (and)
> declared nevertheless more (had) come-about than he
> (Þorleikr) would want.

I interpret 'to have dealt himself a bad lot in [the/his]
dealings with Hrút' to mean that Þorleik had acted badly;
the next bit would then be 'but said that nevertheless more
[had] happened than he would [have] want[ed]'. Here I think
that <en> should definitely be read as an ameliorative
'but': Þ. acted badly, but (in his defence) he didn't expect
matters to go as far as they did.

> Hrútur og synir hans fóru til sjávar með Hallbjörn.
> Hrut and his sons went by sea with Hallbjorn.
> Hrut and his sons went to sea with Hallbjorn.
> Hrútr and his sons journeyed to (the) sea with Hallbjörn.

Definitely 'went to (the) sea' and not the English idiom
'went to sea', if only on account of what come next. For
actually going out onto the sea I've seen both <á> and
<til>, though I think more often the former, but typically
combined with <út> (e.g., <á sæinn út> 'out onto the sea,
out to sea'.

> Hallbjörn rak þá skyggnur á landið og var augnalag hans
> ekki gott.

> Hallbjorn drove then wide open eyes to land and his look
> was not good.

> Halbjorn cast his eyes then on shore with eyes wide open
> and his look was not good.

> Hallbjörn cast wide-open eyes (see reka, Z5) on-to
> the-land (ashore) and his look (the look in his eyes, or
> what he saw?) was not good.

The look in his eyes, judging by what comes next.

Brian