In one generation or less actually. Especially in Southern states. They actively seek out white partners so their kids are white passing. Their genes arent strong enough to really show when copulate with white people
I don't know.
Texas has tons of Mexicans with roots going back to the 19th century and they talk with Southern drawls and everything but they still kind of operate differently from White Texans.
Of course, there's White Mexicans and White/Mexican mixed people like Selena Gomez too but it seems like Tejanos basically crafted their own identity separate from White/Black Texans.
Similarly, White Cubans in Miami tend to stick with their own and stay in their own enclaves despite the GOP support and their skin color.
Tons of Puerto Ricans here in the East Coast are Americanized and White Passing(I've mistaken quite a few for Italians) too but they still rep their Boriqua identity.
I don't think Hispanics are going to become "absorbed" as quickly as people are saying even if a number of them marry out.