Charlotte, I hope that I can help you with your questions. Here goes...
1) I believe that the RHPS crowds' reactions come from their own personal feelings about the 2000-2001 Broadway version of the show. Unlike other RHSs, this one seemed to be willing to take a little bigger chance with the choices that they made. There were the changes within the casting, like having Joan Jett play Columbia, that seemed to deviate from what was expected. For many people, these changes didn't pay off, but I've also heard from several people that went to see the show that either loved it or, at the very least, thought that it was a good show. Also remember that it's usually the angry people that tend to have the loudest voices. Personally, I never got out to NYC to see the show so I can't really comment on it, but I think if you took a wider cross-section of the RHPS world, you might find there are more people that like that version of the show.
2) While there are both plot and emotional potholes all the way through the film ("Toucha" is a BIG one), I can definately help you with this. When she first appears, Columbia is exactly what it says in the opening credits, "A Groupie". She is Frank's biggest fan and all of her decisions tend to be rationalized around that blinding love. Then comes the return of Eddie. This is the start of her emotional change. When she sees his return from the dead, she looks like she is going to explode with emotion. Once Frank kills him, Columbia's reactions to Frank are never the same. She has seen his other side, that cruel and malicious side that her earlier blind love would have probably not allowed her to accept was there. Throughout the Dinner Scene and Eddie's Teddy, you can start to see the more forceful emotions coming out.
Then comes the Lab Scene that precedes the Floor Show. While all of the other members of the house still seems to be following along with Frank, it's Columbia that confronts Frank about the ways that he's acting and what he's done in the past. Then, during her Floor Show solo, her verses sound more of regret than anything else. She talks of the past wistfully ('It was great when it all began, I was a regular Frankie fan') but that emotion disappates as she sings about 'the only thing that gives me hope is my love of a certain dope'. While her "Groupie" blind love is still there, you can see that the events of the film have taken their toll emotionally on her and now she's a much darker character.
Let me just say that these are my interpretations of what Columbia's emotional development is in the work. Your mileage may vary...
3) I believe that their appearance as the Church workers was both a slight nod to the later scenes and also a way to not have to hire any more performers.
4) Since I don't believe that I know you, I will take a guess at why people are reacting the way that they are to you. It is totally possible that some people might feel that you haven't put in the time that you should have to be saying or doing the things that you are. To these people, you still haven't, as the metaphor goes, "earned your stripes". The longer that you are involved, the less that this will happen. Just give it time and I think it will get better.