You are allowed to bring food to eat outside the venue. You can also drink but its suggested to hide it in a party cup.
The official parking for Hollywood Bowl is a nightmare. It will take you forever to get out so if you are planning to go to Tahoe, avoid this lot.
About .5 miles away (south on Highland) from the venue is a mall (Hollywood and Highland) Lots of places to eat and drink here too. Also there is a paid parking lot here thats a lot easier to get out. For those who have not been to LA, on the 1st and 2nd floor of the mall, there's a great view of the Hollywood sign. This is also the location of the Grauman's Chinese Theatre. There is a shuttle that costs $3-5 r/t that will take you from Hollywood/Highland up to the entrance of the Bowl. All the shuttles back are at the bottom of the hill from the venue to go back to the complex.
If you are early and on a budget there is street parking off highland. IT IS VERY LIMITED so get there very early and be patient if you cant find a spot DO NOT risk it, you will be towed. Also, watch the signs and make sure it is a free zone and not a parking pass zone.