If you don't have a decent street map of SF, get one ASAP.
You didn't say where in SF you're staying so its kinda hard to point you in a direction. Lombard St is super easy to get to. Take Van Ness (one of the city's main North/South streets) north and you'll literally run into Lombard. Turn right (go east) and in a few blocks you'll be twisting and turning. Turn left (go west) and it'll take you right onto the GG Bridge.
Definitely drive across the GG bridge into Marin Co. One of the first exits across the bridge is a turnout to a lookout point back across the bay. Absolutely positively a must-see, esp if the weather is nice. It's a spectacular view so you'd better take pics.
Back in the city, the NE perimeter road is called The Embarcadero where all the piers are. Pier 39 is the touristy part and worth a visit if only to see the Calif Sea Lions just hanging out. There's an aquarium on the pier too if you're interested.
Food? I think SF is one of the best food cities in the nation. What kind of food do you like? One of the best hamburgers I've ever had was at Barney's Burgers in the city.
http://www.barneyshamburgers.com/ for locations. But there is something for everyone in SF. The Palace Hotel has an unbelievable Sunday brunch, if you like to tear up that kinda thing.
Parking? HA! It's just like every other densely populated big city. Park whereever you can find a spot. Whatever it takes. Simple as that.
If you have the time, drive east to Danville and check out the Blackhawk Museum. Definitely worth the drive.
http://www.blackhawkmuseum.org/
Hope this helps. It's a cool city, enjoy!!