He seems to have been really anti-social. He did three recordings at BBC studios, and they were going to promote the songs, but he never finished enough for an album. At one point, he sold his rights to the songs he had done up to a certain point--up to about 1973, i think. Gilmour wanted to keep him with the group as a non-performing song writer, but he proved to be really unreliable.
Yes, he was a painter, and apparently continued to work after he returned to his mother's house. He lived there after his mother died, and continued to paint. I've never tried to find his stuff, so i can't comment on it.