co-sign. from what i've gathered, most places are ok with a novel excerpt, but prefer the opening chapter and they expect that it not require set-up/context, should be able to speak for itself. you should definitely/must include a short story or two (depending on where you apply), and that's what will give them a sense of your ability to tell a story.
I would refrain from mentioning anything related to a publisher or publishing, let your work speak for itself. you could inadvertently shoot yourself in the foot by making it seem you have things all figured out. in all the work they review they're looking for potential, to help you grow and get to the place of publication. to say you feel you're at a place where you're ready for publication would lead some to question, then what can we do for you? caveat, my comments are geared towards novels, most places love to see published short stories! shows commitment and hopefully talent!