Catholic Brides

Definitely talk to your priest and even call the diocese to be sure. FH and I were looking into this (Church might not be able to marry us on the date we want) and they said we needed to get 'permission' from the diocese to get married outside of the church or else we would be considered 'defective' (I am not joking!) and we would have to do other paperwork before getting married in the church.

Just double check- I have the name/number of the woman I spoke to in the diocese. If you want the info, FM me!

Yes you can. You do not have to put vow renewals on the invites.
I am already married technically. We did it at city hall in June 2010. No one knows, except a few people (and all of LIW!!) We are planning a regular wedding for October 2011 in a church, it is no problem.