Hi Murray & Kat,
The first site I would look at for info on Carolan is Lesley's wonderful Carolan page. Also check out her other pages for some great tunes.
As far as I know Carolan played a lap harp, and also maybe a larger one, both Celtic harps and not pedal harps.
I can check this in a book I have. I don't think that the harps around that time had levers, but I might be wrong about that. The pictures I have seen of Carolan show him playing the harp in the normal way, not like an autoharp. He may simply have been portrayed that way to show the harp clearly from a front-on angle, or, depending on when the picture was painted/drawn, or how much knowledge the artist had of harps, the harp may be misrepresented in its shape or the way it was played.
There is a well-known (among harp people) painting of Carolan which shows him playing a harp in the normal way, and if I can find the copy of it on the net which I saw a few months ago I will post the site address here.