as far as a carbon filter (which i havnt used yet) you can just attach it to a fan and leave it in the closet to remove odors. with a standard 4-6-8 in" filter a fan will come in those sizes too. your room will still need to be ventilated in some way, a door open during lights on or a small fan or passive ventilation(a place where air can come in the bottom and a hole near the top to exhaust hot air)
topping is really easy. if you just want to pinch off the very top set of leaves you can, or if you go a little lower and take off some growth you may be able to clone the top.(use scissors or razor blade for this) just find the right place on the stem to cut it. this is as simple as i can get.