Knights of Tezoth

did they ask about the explorer's journal? what should be written there?

Anything regarding your own personal new discoveries.

and the gourmet's journal, I understand, is purely for food. and do I have to describe it in detail or can it be funny?)

Well, generally, just write it however you want.

is he good? not a combatant?

You won't know until you start.

can a friend be of any origin or must they be the same?

Any.