Take a softside cooler that is small enough to fit under your seat, anything bigger and you cant bring it in. no glass bottles, no outside alcohol. Can take food or drinks in otherwise. I believe bottles must be sealed, but not positive on that. several restaurants around the area. Coming from Plano on a Sunday you should be good to take 75 south into downtown and cut west on 30 to the ballpark just follow the signs. You can park on at all 4 sides of park, closest to your seats.
No CCW, but Ive never had a problem carrying my pocket knife in. In fact, got wanded and guy commented how nice my ZT knife was. Arlington PD also maintains a strong presence there. Dont get in a fight in the parking lots, they get there quick. I saw the aftermath of a fight and there were guys cuffed all over the place.