I am glad this thread was brought back alive, as I have the exact same question. I am still waiting to hear back from the WC, but glad to see these posts.
For us, it was a coincident. Paul is catholic and his parents are moving back to China early next year, before our DW. So we're going to have a catholic ceremony here in the states in Dec. However, to me the April ceremony is the REAL one and I want everyone else to see that ceremony as our wedding. So for those who have gone through this already, other than the paperwork and officiant, the rest of vow renewal ceremony is exactly the same as a wedding ceremony? i.e. vow exchange, sand ceremony, etc, etc...