Yes it is. Don't know about the park.
Yes the only tour available that actually lands and lets you walk on the island. Other tours only drive by the island on boat. Parking is pretty bad so they recommend you use public transportation to get there. If you want to park check out the Tour website
Yes, this is the only service to Alcatraz. Parking is bad in San Francisco so if you can, get a space as close as possible and leave time for walking or taking public transport.
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