> snýst hann innar eftir búðinni.
> he turns more-inwards along the booth.

MM & HP: "At the door he turned once more"

> hleypur hann innar eftir búðinni
> he runs more-inside along the booth

MM & HP: "He ran back into the booth"

> Þá lukust upp augu hans.
> Then (it) opened his eyes (ie his eyes opened).

Not impersonal. 'lukust' (='lukusk') is 3rd person indicative plural,
agreeing with 'augu'.

'lúka upp' + dat. or acc. "to open [something]" (transitive).
'lúkask upp' "to open, be opened" (intransitive)

Hildr fór til dyranna ok lýkr upp hurðunni
"Hildr goes to the entrance and opens the door"
[
http://www.heimskringla.no/original/fornaldersagaene/halfdanarsagabronufostra.php
].

Kletturinn lýkst upp og hún sér veislu huldufólks.
"The cliff opens up and she sees a feast of the hidden (fairy) folk."
[ http://www.hi.is/~gt/sagnavefur/100sagnir/ljuka.htm ].

> stóð á hamri og kippir að
> stood on (the) hammer

See CV 'hamarr' Beta: "The back of an axe" [
http://lexicon.ff.cuni.cz/png/oi_cleasbyvigfusson/b0235.png ].
MM & HP "right up to the hammer", not a term I'm familiar with in
English - the diagram in the Wikipedia entry suggests "poll" or "butt"
[ http://en.wikipedia.org/wiki/Axe ].

> sem augu hans höfðu upp lokist
> as (when it) had opened up his eyes

Not impersonal; see above. 'höfðu' is 3rd person ind. pl., agreeing
with 'augu'. The intransitive verb 'lúkask' agrees with the nominative
logical subject, e.g. 'hús hefr upp lokizt' "the house has opened up".
It's just the simple verb 'lúka' that can be impersonal:

'því var lokit' "that was finished"
'var lokit þinginu' "the assembly was finished"
'er jarl hafði því upp lokit' "when the earl had made it known"
'áðr en lýkr' "before the end comes"

> mjög ákveðið
> much fixed

MM & HP: "foreordained"

> "því að slíkt er mjög ákveðið en viðvörunarvert ef slíkir atburðir

verða að stinga eigi af stokki við þá er svo nær standa."

> `because such is much fixed (ie meant to be) but a warning (?)

(that), if such occurrences happen, to not push away (see under
stinga, Z2) those who stand so near (ie close relatives).'

MM & HP: "because such things are foreordained. It is a warning to
others in similar circumstances never to rebuff those who are so close
of knin."

CV 'stokkr': 'stinga af stokki við e-n' (mod. 'stinga e-n af stokki')
"to prick one out of one's seat".

> féllu hálfar bætur niður fyrir sakastaði þá er Ámundi þótti á eiga.
> half (the) compensation fell down (was denied?) because of (the)

grounds-for-suing which Ámundi seemed to have.

MM & HP "was remitted". I'd translate 'þótti' "was considered" here,
rather than "seemed".