-- Is it a full-morning commitment? What times should we plan on being there for the 1PM show? IIRC the ticket info says to show up early morning, then come back at 9AM for the 1PM show. What do we do between 9AM and showtime? Can we get lunch nearby or at CBS?
Yes, attending a taping is a full-morning commitment. The 4-hour wait is necessary for the pages to check ID's, write name tags, and for the contestant coordinators to do 15-20 second interviews with the entire audience (15-20 seconds x 300 audience members is close to 2 hours alone). I'm not sure on the lines as of now, but you may need to show up a little bit earlier than 9 AM to guarantee a seat in the studio... perhaps 7-8 AM to ensure you don't get bumped out by the groups that are pre-booked, since ticket distribution is in excess of capacity.
CBS has a snack bar on site that you can visit before you go through contestant interviews, and you are allowed to bring food while waiting on the CBS lot, but you are not allowed to bring food inside the studio. Keep in mind that after 9 AM when you receive a contestant card, you are not allowed to leave the lot until the taping is over.
-- It says no cell phones are allowed. Is this the case, or is there some way to have one while in line and waiting?
The CBS pages will ask you to put your phone away in your car, but if you forget, you can check your phone in with security and pick it up after the taping is over.
-- How is the parking situation at that nearby shopping center? Will it be fairly obvious where to park and how to walk to CBS?
The closest parking area for Price is Right is the Grove Shopping Center parking garage, right next door to CBS television city. The last time I was there 4 months ago the parking rate was about $22/day. From there, it's a short walk to the gate at CBS television city on Fairfax Avenue - look for a ticket booth and pages in red jackets to check you in.