New grow room. Need help with design and what I need.

I have a 14ftx10ft room and the cealing is 8ft high that I want to turn into a grow room. it has an 8ft window that opens up 2ftx4ft6in on both sides. I want to grow 6 plants 3-4ft tall. so I would probably be using 5ftx5ft space for the plants. I have one 400watt hps light setup already and a 270cfm exaust fan and some duct. I was wondering should I get another 400watt hps and use 2x400watt hps lights for 6 3-4ft plants or get 1000watt hps and just use that. also I have a 21inx21in house fan that I was thinking on putting in the window to bring fresh air in and use the 270cfm exaust fan on the other side of the window with duct attached to it lined to the other side of the room on the cealing to take the heat out of the room because heat rises. but the thing is how would I block out the light from the window during flowering and still get air coming in and out of the windows? and also light shines underneath my doors in the bedroom I have a bathroom door and a bedroom door that I would need to seal the light from. What else would I need for a grow that size? any tips or pointers would help me alot. this is my first bigger grow. I usually grow 1 plant at a time. which is getting kinda boring I want more yield and more plants to take care of. I have a $400 to $500 tops spending limit. I hope to not have to spend that much tho. I know I need to get pots and soil and nutrients. but is there anything else that would be needed or any ideas of how I could arrange this setup? Oh I also have a 14ftx3ft closet that I use for my vegging room but turn into my cloning room on the left side of the room. i would need to seal light off from the closet also. I also have a 56inx3ft grow tent that I could turn into my cloning room if it would make things easier. Thanks for the help in advanced.
This is what my room looks like
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