I really don’t think I’m calling on the authority of religion at all. I list a number of religions and philosophies of life that arrive at similar conclusions. I consider religions, in this context as types of life philosophies.

Virtue (aka wisdom, in this context) is a worthy goal, following Socrates, because it is the only thing that is always good by definition, and that therefore allows us to use everything else well. The argument is outlined in Plato’s Euthydemus: https://howtobeastoic.wordpress.com/2015/08/20/why-platos-euthydemus-is-relevant-to-stoics/

No, virtue, meaning and happiness are not equivalent. But virtue does provide meaning, and a meaningful life is one kind of happy life. There are others. See here: https://www.indiebound.org/book/9780525566144