A question from a Lutheran, who thinks the answer would be helpful, but not necessary to salvation:
How would the nature of the Holy Spirit be different, if the Orthodox happen to be correct, and the Spirit proceeds only from the Father and not the Son also? Since the Holy Spirit cannot have an "origin" because of His coequal status with the Father and the Son, how does the process of His "proceeding" affect His nature?
chajin: See link below, paragraphs 246-248 I think address your questions directly.
http://www.scborromeo.org/ccc/p1s2c1p2.htm#III