"Whiteness" is absolutely physical/biological, but if you want to talk about characteristics signifying traits associated with power and dominant status, then yes, they are socially constructed. It's just not called "whiteness."
Actually not so much. In late-19th early 20th century, Italian, Greek, Bulgarian, etc immigrants were decidely labeled as "non white" -- to the point of lynching when one of those "non whites" were e.g. found dating a "white girl" (white being mostly WASP).
> if you want to talk about characteristics signifying traits associated with power and dominant status
Whiteness is associated with power and dominant status, but not all categorizations of "characteristics signifying traits associated with power and dominant status" are Whiteness. Whiteness is a subset of CSTAWPADS.
