Can we just go in there without seeing the concert and look around? Also, how much will parking be?

Hello yes you can do it and do not forget to visit the Broad museum Is next to it and it Is free.

Absolutely, you can go in and look around but only in limited areas. There is also a cafe and gift shop located on the ground floor.

Yes you walk around in the entrance area and go inside and even buy snacks, however not go up to the outside of the seating areas (there's attendants checking everyone's tickets before you go up to the different seating areas), and parking was $9 per vehicle when we went last month.

There is free admission, you only have to register when you arrive. You can see the building inside and outside with audio guides. The concert hall can not be visited if they are rehearsing. Parking the car there I do not know if it is possible but I would go a bit further because in that area they are very expensive.