It is definitely OK to have work in progress and discuss it in your application come September. In fact, I'm pretty sure most people will not have a publication or poster presentation by then unless they started to do research in ophtho very early. I personally shot to have the paper at least "submitted" by application time. Of course its best if you can say that a paper is "submitted for review" or even "accepted" or ideal if you can cite a reference, but dont sweat it if you don't.
More importantly, be able to discuss your research in depth at an interview as this can often times be an important focus of your talk.
Absolutely! Research takes commitment and dedication. All too often people may list projects in which they were peripherally involved or are just listing for the sake of strengthening the application. Filling out an application is based on the Honor System and committees know this. In order to stand out, you must know the crux of your research cold. In addition, you may be involved in a large project in which you had a smaller role (similar to the situation I was in) People may directly ask you what exactly you did as I was often asked. It goes without saying...but dont overglorify your role in anything!