I was a bit worried about the temp of the ceiling being higher than other ceilings in the area and standing out should it be frosty or snowy etc?
do you think these LEDs would have any affect on that.. also with blowing out the added heat from the heater that will be running?
Nah - the LEDs will have no effect on that. They give off less heat than your television set.
I would just exhaust through a filter into the room _ rather than trying to exhaust through air vents in the wall.