Lee Bailey has the >, I have the >>.

>>1. Who is Örvandill?
> Arvandil the Brave?

>>2. What is a sole-twig?
> A toe?

>>3. What is Örvandill's sole-twig?
> A star?

Quite correct.

>>4. What is an Örvandill's sole twig of deep water?
> Gold?

That's right! "Fire of the sea/river" is 'gold'.
In our case fire (eldr) has been replaced
with a star (tá Örvandils).

>>5. What is a Sunna of all that?
>
>I'm not sure

Oh, come on:) It's the same as "Hlín of silver",
"Hildr of clothes", "Frigg of silk" etc.

Regards,
Haukur