Which catter owns a harpoon?

My guess would be Naemanson.

Name at least two 'Catters (besides myself[Rapaire]) who can play trumpet, the instrument of the angels?

BARKY is one,

Who is the Mudcatter you shouldn't approach with a sword (unless you really know what to do with it)
Rapaire is another answer

and I can't find the original question - but Rapaire would also be the mudcatter librarian in the hinterlands of the US.