>> "Vilt þú gefa mér þá," segir Gunnar, "og hætta til hverju eg launa þér?"
>> "Do you wish to give them to me," says Gunnar, " and risk until when
>> I reward you?"

> I think, here 'þá' = "then" (in the sense of "so, in that case..."):
> "Will you give me [hay and food] then?" The two items are neuter
> (hey) and masculine (matr) respectively, so presumably they would
> collectively need a plural pronoun, rather than masculine: compare
> 'bæði mat og hey' later on in this section.

I think this 'bæði' is usually regarded as a conjunction - you'd use the
same form even if it was "bæði Pétur og Hauk".

As for two items of different genders triggering neuter it's true enough
but it can be tricky in practice. Let's try to translate these four
sentences (which I assume are reasonably normal English) into Icelandic:

1. Eyes are useful.
2. Feet are useful.
3. Eyes and feet are useful.
4. I have useful feet and eyes.

1. Augu eru nytsöm.

The noun is neuter, so is the adjective - no problem.

2. Fætur eru nytsamir.

The noun is masculine, so is the adjective - no problem.

3. ?Augu og fætur eru nytsöm.

This sounds awkard and clumsy. I'd usually try to avoid constructions like
this; in this case one could say something like "Augu og fætur eru nytsöm
líffæri" to dodge the problem.

4. *Ég er með nytsöm fætur og augu.

Woops! This is just wrong. I don't know why you can't say that but you
can't. What you can say is:

4.1 Ég er með nytsama fætur og augu.

This is ambiguous as to whether only the feet are useful or whether the
eyes are too but we'll have to live with that. The English sentence has
the same ambiguity.

Now, translate the following into Icelandic :)

"I do not like
green eggs and ham.
I do not like them,
Sam-I-am."

Kveðja,
Haukur