The second from the top photo seems to show the typical lacebug excrement. The top photo, however, seems to show more than just lacebug damage. It's not clear in the photo, but the stems show what looks like either aphids or scale. Mites are too tiny to show up well, but there don't seem to be any webs (which are not produced by all mites) present, at least that I can see. At this point in the year treatment for lacebug, except raking up and disposing of fallen leaves, is not necessary. The same would be true for aphids. Scale is another story. You really need to have a branch or two examined by your county extension service or state agriculture department. They can also recommend best treatments for now, if needed, and next spring to prevent infestation next year.

The bottom photos all show the normal yellow discoloration that rhododendron leaves acquire just before they are naturally shed. The spots are produced by fungal infections, but identifying which of the dozens of types is not really possible without laboratory analysis and is not necessary. Rake up the fallen leaves as above. This can help, but most rhododendron growers just ignore the spotting on leaves that are about to fall anyway.