I live in Newport Beach. I agree with most of what LT Dan had to say. However, in terms of traffic: a) it is always bad, and b) some times of the day are worse. I would say to get out of Beverly Hills by 2:00 PM, and certainly no later than 2:30 PM. The evening "rush hour" tends to start right about then. If you are leaving in the morning have a nice breakfast and leave around 10:00 AM or later.
The water temperature will be a little below 60 degrees. See
Laguna Beach (CA) Water Temperature | United States | Sea Temperatures You can go in but you do need a wet suit. If you are staying in a high end resort the concierge can recommend good surfing beaches for you. Just remember two things: 1) you are going to be here in the rainy season, so there could be rain, and 2) the Rose Bowl game on January 1 draws a good crowd of visitors even down in Orange County, so you might want to make your reservations well in advance. Depending upon the teams we usually get a good number of cold weather visitors.
The Montage is a very good recommendation, but it is quite expensive. The beach near there is not the best for surfing. If you wanted to go a little further south in that price range you can try the Ritz-Carlton or the Monarch Beach Resort near Dana Point. If you want to stay in Newport you can go very high end with the Resort at Pelican Hill. There are less expensive choices in all three locations.
You will usually see surf on the local beaches of at least 2 - 3 feet, but when storms hit the surf can go up to 6- 8 feet or more. Some beaches have even higher surf, so make sure to match your skill level to the beach that you choose. I would stay away from being right next to the piers since surfers have been known to be pushed into the piers. Check out this site for surf reports.
Local surf reports, swell forecasts, and surf cams - Surfline