In the first bat scene it is mentioned that when in bat form vampires are nude, and this is verified in the following scene where Shane attempts to rape Sarah. However, this is ignored for the remainder of the film, with vampires switching forms while remaining fully clothed regularly.
This movie makes it very clear that vampires do not have reflections, but in the scene when Shane corners Sarah Harrison in the bedroom (about 1:25 into the movie), we can see his legs in the mirror on the far wall.