Dear Yong,

> 1. Should mahesii (chief queen) be mahesi (great sage)?

Mahesii meaning the chief consort of a king and mahesii as
an epithet of the Buddha are two different and unrelated
words. The former is formed:

mahiiyatii ti "mahesii" -- "She is to be honoured, thus she is
a mahesii"

while the latter is formed: mahaa + isi = mahesii

> 2. As given on pg 114 of the book, lokahito is a Tappurisa:
> lokahito = lokassa+hito, beneficial to the world
>

> 3. The subject of the first pair is hence:
> naatho lokahito mahesi: the Great Sage, the Protector,
> one who benefits the world.

Possibly, but I'm not sure. I am used to seeing lokahito in
the dative form lokahitaaya, "for the benefit of the world".
I don't know if it can also mean a person who benefits the
world.

> Therefore, the sentence would be:
> "Attha.m hi naatho sara.na.m avoca."
> "The meaning (is) truly the refuge," spoke the Protector.

Yes, I think this is right. Concerning the first two lines
as a whole, another possibility occurred to me. We could
divide them into two sentences, and take avoca as a
predicate that applies to the main subject of both of them.
An ellipsis like this is not uncommon in Pali verse:

attha.m hi naatho sara.na.m avoca
na bya~njana.m lokahito mahesii

"The meaning is truly the refuge," said the Lord;
"It is not the letter that is the benefit for the world,"
[said] the Great Sage.

Best wishes,

Dhammanando