30-35% is great, especially for plants in late flower with heavy bud development. She'll be right to keep bud mould down.

NL can be stinky, but I agree with you, it's not as pungent as some I've grown, like the Sweet Tooth #4 I'm running now. The ideal for security's sake is zero scent, but you're the best judge of your situation. If you think that unfriendly noses won't pick it up, that's your call. Apartment life can be dicey when growing because maintenance can let themselves in to most apts without notifying you.

Carbon filters are simple to fabricate and are very effective, at least until the carbon needs replacement. I like UV ionisers because they don't impede airflow like filters.

Your call, matey, but it's always smart to give the bastards nothing to go on.