I've always pronounced "Ceanothus" as "Key-An-Oh-Thus", with the
emphasis on the "An". Is this correct, or am I completely wrong
(does
it have a soft C for example).

My neighbour pronounces "Cotoneaster" as "Cott-On-Ee-Aster"
(Emphasis
on the "Ee") whereas I have always thought of it as if it were the
two
words "Cotton-Easter" - is he right and me wrong again? :-)

My old latin teacher used to say it didn't matter how you pronounced it
as it is a dead language so as long as it is written correctly we were
fine!!

That said "c'tony aster" and "key a noh thus"

Jay