I would still believe everything I believe as a Catholic if I wasn't Catholic/if there was no Catholic Church. For example, I am not opposed to abortion "because I'm Catholic." I don't believe waiting for marriage until one has sex is the ideal choice "because I'm Catholic." I don't like when people say that. I don't know if this was the type of argument you and Vander were having but that's what it seemed like.
Not really, no.
I also think you might believe in the Catholic religion a little less if you weren't Catholic.
My point was, assuming you had a pretty conventional sense of morality (which I don't think varies much when it comes to religions), I doubt you'd personally decide that homosexuality is wrong without your religion dictating that to you. Maybe you would, but I rarely see that happening with someone who can defend themselves on non-theological levels.