As someone who lives in a legal state, there is no such thing as growing weed stealthily indoors. Your entire house will reek, no matter how many carbon and HEPA filters you use.
Depends on a bunch of factors. I once grew a plant that yielded around an oz (after drying) in my closet with a fan and lights on a timer and no odour control. That plant ended up bigger than most computer cases by the end, though it would have fit in one until about the last month or so.