Milwaukee Seating

I’m attending my first Indycar race this weekend at Milwaukee, and I got the standard GA tickets online. I was wondering how strict they are about moving around in the stands/aisles. I’m bringing a small point and shoot and I’d love to get as close to the fence as I can for some photos. I also saw somewhere that you can access the infield during the race, is this correct or do you need a certain ticket for that? Regardless, I’m super excited. Thanks in advance for any info!