if its spraying then your puting millionbs of particals in the air which you can breath in which is dangerouse. but rolling it on shouldnt be to bad at all just try and keep a supply of fresh air entering your room. as for the behavior of the primer if roilled on i dont no but i primered a car up with celu primer and i brushed it on and had no problems at all apart from brush strokes. itr didnt matter anyway as there was allot of filling and sanding to be done to it. hope this helps
or you could try contacting the manufacturer of the primer and ask them. they should know if they made it as they should have tested it for suitable application process.