As with any new plant, you should keep it isolated for a few weeks, just in case. Onc. Generally need a fair amount of dappled light. You should research the light requirements of each of your orchids to ensure that they are getting sufficient light to bloom. Of course if they are re-blooming - don't change a thing
Watch the mid-day sun since it can be quite strong. You can touch the leaves when they are in the sun and make sure that the leaves are not overheating.
I suspect that the spots are just what Oncidiums do. Maybe someone who know more than I do can chime in.