> Grace wrote: "Well this is interesting. Apparently sjór félli
could mean the tide ebbed or rose."

When the subject is water, rivers, etc., it often makes sense to
translate 'falla' as "flow".

Patricia queried: Hvorki skorti þar lax í ánni né í vatninu

You got the right idea, "Neither was there a lack of salmon in the
river nor in the lake". The modern spelling 'hvorki' = ON normalisd
spelling 'hvár(t)ki'. And 'hvorki ... né' = "neither ... nor".

> að því er þeim sýndist

"as it seemed/looked/appeared to them"

The other bits you underlined look fine to me, Patricia, but 'fjöru'
is the dative of 'fjara' "ebb" (also means "shore", the part of the
land that's covered by the tide) - nothing to do with the four
cardinal points, as far as I know. And 'þar er á ein féll úr vatni
einu' = "where a river flowed out from a lake". "á' = "river". 'féll',
= 3rd person singular preterite of 'falla' "to fall; flow (of water).
You were thinking of 'fjall' "hill, mountain, fell".

> Nú vil eg skipta láta liði voru í tvo staði og vil eg kanna láta landið

Jack wrote: "Now I want to let the company divide to be in two groups
[can't really work the grammar of this bit] and I want to allow the
land to be explored"

'láta' often means to have something done, or cause something to be
done, or have something done on one's orders (rather than just
passively allow/let it be done), so you could translate it fairly
literally as "I want (to have) the company divided in two and I want
(to have) the land explored".

All the verbs here are infinitives except for 'vil'.

'skipta e-u í tvo staði' "to divide something into two"
'skipta láta' = 'láta skipta' "to have (i.e. cause/order to be) divided"

'kanna landið' "to explore the land"
'kanna láta' = 'láta kanna' "to have (i.e. cause/order to be) explored".

Both word orders are possible in Old Norse, so it's the same as
saying: [nú vil eg [láta [skipta liði voru]]] "now I want our company
divided/dividing" and [og vil eg [láta [kanna landið]]] "and I want
the land explored/exploring".