Do I want more air going out or more air going in to my room to create a negative pressure? More exhaust or more intake?
There's an amazing thread titled ventilation faq that will answer all of your qs. But to answer this one, in order to have neg pressure you need a airtight cab with an exhaust fan blowing out somewhere high in the cab (bc heat rises) and a passive intake (a hole or two) on the lower opposite side from your exhaust. This will promote good airflow and neg pressure. Putting a intake fan will interrupt the neg pressure so passive is the way to go. Is def read over the thread ventilation faq for sure tho. Good luck.