2. About 17 IIRC (maybe 18). None of the mainland parties run. Main parties in NI: DUP, SF, UUP, SDLP
Its 18. The Tories occassionally run candidates, though I don't know when they last held a seat in NI, probably before the end of Home Rule. Also note that the Alliance Party has representation in the Northern Ireland Assembly.
I used to be one of the Wet Tories, but as you say there's very little room for us in the party these days; Basically we have to find room in the Social Dem wing of either the Libs or Labour.
I think they are due for a comeback in Wales at least in the coming election as they have been doing quite well in the Assembly elections there (up to 11 of the 60 seats now)