Though I have heard tales of Californians being native speakers of Lisp, this is probably just a rumor.
That's true of most Californios, sure, but they are, by far, a minority of California Hispanics, who are mostly from families that immigrated much more recently.
Depends which other parts. Disadvantaged compared to German or Dutch speakers, and even French speakers, but, sure, advantages compared to other, say, people whose only prior language is Mandarin. And, of course, a big disadvantage compared to immigrants who already speak English, even if it's not American English.
But still very far from starting off even functional, much less halfway to native fluency.
I wouldn't understate the significant advantages.
> And, of course, a big disadvantage compared to immigrants who already speak English, even if it's not American English.
Not necessarily. A large percentage of children of immigrants speak with their family (nuclear and extended) mostly in their native language even if their parents can speak decent English. The English skills don't transfer much unless the parents are very active in their child's English education.
http://bigthink.com/strange-maps/a-map-of-lexical-distances-...
[0] https://en.wikipedia.org/wiki/Demographics_of_California
So having difficulty with English is a really, really bad thing for these students.
Eventually both are needed - as well as computers - but how to get there, opinions can differ widely.