Hello, I run a sealed room with Co2. The fan with a filter cycling in the room is only good for circulation and scrubbing the smell, unless you have it hooked up to a HEPA filter in which case it’s also good for cleaning the air of pollen and mildew spores ect..
if it’s a sealed room then yes you will need co2, I run a generator and have it set at around 1000-1500ppm depending on the ambient room temp.. once you get good at balancing all your room parameters then pushing up your vpd will increase yield but it can be like walking a tightrope.. I love it, but it’s a lot more relaxed and easy at your current temps so do whatever makes you comfortable. (And the question about venting the dehumidifier air.. no, don’t have to. Just take into account it’ll raise room temp slightly)
Oh, and I have run RDWC in a high temps room, just added a chiller and had the brain res set up out of the room.
Nice setup!