It is really your choice. I don't think it's weird because gatecrash is the Chinese custom and unveiling is not really getting married. Church itself has it's procedure, so it's nothing wrong to unveil again.
As for the tea ceremony in church, it's very common to do it in a room at the church. It's again a Chinese custom. As long as you are clear the objective of the tea ceremony is to respect your elders, doing it wherever is not very important unless your parents are very traditional.
But come on, let's be realistic, you also want your guests to travel back and forth the church?
Do what makes sense to you.