The local astronomy club, Halls Valley Astronomical Group, holds a monthly star party there, usually the first Saturday after a new moon. www.hallsvalley.org
Yes it is dark enough for stargazing because there are no surrounding lights (such as from buildings, light posts, or street lights) to mask the stars.
Mostly, but depends on time of year. Check out their website for more details- https://www.sccgov.org/sites/parks/parkfinder/Pages/JosephDGrant.aspx
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