So I'm thinking of using sound board to help with light leakage and noise control. Do u guys think it will help cut out the fan noise. I'm also using CFl nod led so I don't think I'llhave leather issues
Depends, but doubtful. Much of fan noise comes from vibrations the fan sends into other materials, not from the fan itself. Vibrations are much lower frequency and probably wouldn't be stopped by sound insulation (ever been in a movie theater and you can tell when there are explosions in the movie in the next theater over? You can't hear that other movie's dialogue or gunshots but you sure can feel the rumble from the explosion sound effects). If you have noise from the air itself then you would need to insulate not just the box but the exhaust pipe as well. Try suspending the fan in place by string or something so that it isn't hard-connected to the wall in any way, that will cut out vibration noise.
get the sound board. It will work for what you are doing. My room is different for sure but soundboard makes my room super quiet. It doesn't cost much. I can stand right next to the entrance of my room and no sound. This winter I have a heater/fan combo, 400 watt ballast, cicrulating fan and an S&P exhaust fan and hear nothing. My walls are 2" thick with regular insulation, soundboard on the out side, sheetrock on the inside and reflextix covering the sheetrock. I did the ceiling that way as well. good luck