St. Joseph's death lacks definitive revelation, and the Church doesn't endorse apocryphal writings. Tradition suggests he died before Jesus' ministry, surrounded by Jesus and Mary, but this is not essential for salvation.
The Novus Ordo is a valid Mass when celebrated according to the prescribed norms and with due reverence. You are certainly welcome to attend. It represents the sacrifice of Christ, and through it, you can derive many spiritual benefits while receiving the Lord in a sacramental manner.