OK... so my boyfreind has red hair and I have dark brown. My boyfreind is full white, and I am half mexican and white. Wich color hair are my kids more likely to have?

The darker is usually more dominant so probably the dark brown

NO is correct. With both eyes and hair, the darker colors are dominant. But that doesn't mean you won't have a red-headed child, just that it's less likely. (My mom's eyes were brown, Dad's blue. Only 1 of her 4 kids had brown eyes and they were hazel, not brown)