1) It's absolutely a sport
2) I already liked NASCAR enough before, but my first race really opened the door to how awesome it truly is in person. Been going every year for probably 9 years now, and plan to go to a lot more and see as many tracks as possible over the next 10 years.
Before my first race in person, I casually followed it, watched the big races, etc.
After my first race, we start making it a full weekend every year(sometimes twice when A&M plays road games in November on that weekend). It's the only sporting event where the entire weekend can rival a weekend of Aggie Football at Kyle Field. It's important to embrace the culture, check your pretentiousness, ego, and pride at the gate, and have a great time with good friends.