It doesn't affect me nor my wife, even my mom who is not into extreme rides by any stretch was fine on this... honestly, everyone in my family has been fine on this ride so far...
However...
I have had several instances on this ride with strangers and vomit, so yes I would think it does affect some people.
I would also agree with some of the other posters, it is likely the screen that causes it - probably worsened because it is a tad fuzzy these days.
I would also highly agree still going through the queue! It is one of my favorite parts of the attraction, great detail (probably the best in all of Universal Orlando parks) and if you are a Harry Potter fan, this is the meat of it - there is so much in the lengthy queue to see!
And on the scary images question, not so much IMAGES, but there are actual animatronics that will certainly deliver a few jumps (worse depending on where in the cart you are sitting). I would actually say... %80 of the ride consist of the darker parts of the Harry Potter franchise, which happens to be the only thing I wish they would have truly done different, but here nor there. If this becomes the hold up, I would go to youtube and watch a ride through to judge for yourself.
Great ride if you do choose to ride it, but I would also hate for you or your daughter to ride it and it ruins the beautiful WWoHP visit for you :-/