> Hann fer til Hafratinda og tók hús á Þorkatli.

> He goes to Hafratinda and took home Thorkatl. (?)

> He goes to Hafratinda and seized Thorkell’s house.

> He goes to Hafratindar and rushed (the) house towards
> Þorkell.

I'm with Grace on this one: I think that <á Þorkatli> is
functioning as a possessive, attached to <hús>.

> Engu lét Halldór ræna og fór heim við svo búið.

> Halldor let no one deprive him and went home with so may
> be. (?)

> Halldor did not allow any theft and went home as matters
> stood.

> Halldor caused to plunder nothing (ie they left the house
> untouched) and went home, things being so (see under
> buinn).

The implication of <við svo búið>, I think, is that he did
nothing more -- he just went home at that point.

> Steinþór Ólafsson bjó á Dönustöðum í Laxárdal.

> Steinthor Olafson lived in Donustad in Laxardale
> (Salmon-river-valley).

> Steinthor Olaf’s son lived at Donusteads in Laxardal.

> Steinþór Ólafr’s son lived at Dönustaðir in Laxárdalr.

So far as I can discover, the etymology of <Dönustaðir> is
uncertain, the likeliest possibilities being that it was
named after the original (or at least a very early) owner, a
woman named <Dana>, and that it gets its name from the
rushing, thundering noise (<duna>) -- I presume of water --
in a nearby ravine.

> Þorkell kuggi (Cog?)

Yes, it's likely that <kuggi> is a weak side-form of <kuggr>
'cog, merchant ship'; the word is a borrowing of Middle Low
German <kogge>, so a matching weak form would not be
surprising.

> Þeirra son hét Steinþór er kallaður var Gróslappi.

> Their son was named Steinthor, who was (also) called
> Groslapp.

> Their son was named Steinthor who was called Groslappi.

> Their son was-called Steinþór who was called Gróslappi.

<Gróslappi> is from the feminine forename <Gróa> and
<slappi> 'tall, lanky person'.

Brian