score:6
There are a few obvious driving routes. The drive will probably take 6 to 8 hours overall depending on where in the city you begin and end.
There is no direct train between Los Angeles and San Francisco. The only public transportation option is the bus (which according to Google Maps takes 16 hours).
There are places to stay (motels) along most major roads, usually in towns. Sleeping in your car by the side of the road or in rest stops is not allowed in California.
San Francisco has good public transit (BART, buses) and a car is not necessary (although there are some places where you might need a car to get to).