I ain’t really sure what you meant. I tried to use rayshadow intead. Now it ain’t any shadows under the stair, but the rest of the halo goes through the wall over the stair instead.
You probably have to set your halo step size to 1. See this thread
No. If you look at this thread you see camera moved to other places. You have to look at the middle of page 6. I can’t set halo step size if I use ray shadow.