Uber and Lyft are the best options from Oakland. From San Francisco airport there is a third option the "Marin Airporter" an affordable bus/shuttle service that runs between SFO and several bus stops here in Marin (you bypass all of SF). For more Airporter info see their website >>>https://marinairporter.com/
The average temperature in late June is 72 Hi, 52 Low with temperatures peaking around 5 pm. When the sun sets the temperature will drop and can become quite chilly. Dressing in layers is a good idea.
Absolutely!