About the civil marriage:
there is official definition of Russian Orthodox Synod (28.12.1998), signed by Alexiy II (russian text is here -
wco.ru/biblio/books/sinod1/Main.htm ). It says, between other statements, that “Church respects civil unions” and that priests cannot claim civil unions between orthodox people to be invalid; it blames priests who deny Communion to these people, and who claim “civil unions” to be adultery.
(By “civil union” I mean officially registered marriage - according to state laws. Though Russian Orthodox Church encourages people to marry in the Church, it doesn’t deny communion to those who are married only civilly.)
I joined Latin Rite. Though I respect Eastern liturgical traditions, I always liked the latin rite Mass. And, deciding to join Catholic Church, I wanted to be in Latin Rite. Besides that, there are (as far as I know) no Eastern Rite churches in St.Petersburg; there are 7 Latin Rite ones (in Moscow, there are only two - so Petersburg is “more catholic” city than Moscow 8)