Chow-worthy, dog friendly, cheapish around Laguna Beach?
First off, it is not worth the drive just to have a bite in line with your limits. If you want to walk around (dogs on leashes are allowed in main beach) and see the community, then by all means come on down, it is a world away from Santa Monica.
But, to match the dog and vegetarian friendly requests, I would suggest Cafe Zinc, though it isn't super cheap. If you eat fish, Taco Loco is good and cheapish and you may be OK with a dog, though I have not taken my dogs there.
640 S Coast Hwy Ste 1, Laguna Beach, CA 92651
350 Ocean Ave, Laguna Beach, CA 92651
There are tons of restaurant that have outdoor seating and would probably allow dogs. I would go down there and walk around, enjoy the day, and see what you come across.
Taco Loco is VERY casual (and small), with non-fish & vegetarian items such as the blackened mushroom & tofu taco on blue corn tortilla with yummy salsas & guacamole.
It looks like http://www.madisonsquare.com/index.shtml allows dogs.
Here's a list but I would call and check first unless you can be flexible once there.