Deep litter oughtn't be any dustier than non deep litter (tho obviously it is dustier than housing chickens on bare wire)... you don't START with the litter being deep, you just add more as required.
The usual knock against deep litter is *moisture*, as indeed it can be a bit damper than regular litter depending on how it's managed and what your ventilation is like... but damper litter is *less* dusty not more.
A fan blowing out the coop window is not going to do much of anything about dust. Either the coop is dusty or it's not, you know? However you do always need ventilation and it should be of a type not to let strong gusts of wind stir up the litter. Fan-operated ventilation is not generally necessary as long as you have a well designed system of 'normal', passive vent openings.
Cheers,
Pat