Congratulations on being selected by the President/CEO as being, in his eyes, qualified to fill the position.
However, your comments above about initially turning down the opportunity is troubling to me. I'm thinking that there are some reasons, in your mind, for thinking about declining the promotion. I have always looked for opportunities of increased levels of responsibility, and subsequently worked to be able to handle he positions. If you feel you are qualified for the position, if you are willing to meet all requirements of the position, and if you are willing to put for 110% toward meeting the job requirements, then why would you not jump at the opportunity.
If your confidence level is less than that required to do the job, then you need to really reflect on taking on the opportunity, given the requirements -- 24/7, etc. -- you have to meet. Are you willing to do the job?
Next, I would suggest asking yourself what it is you want to negotiate, then comparing it with the requirements outlined above by the President/CEO. I would question whether I would want to negotiate reducing the job requirements, given they came for the CEO. He may be thinking a person from within would be more qualified and willing to meet all requirements.
You have some sound advice throughout these responses. I hope my comments, while maybe appearing negative, help in your thinking.
Good luck with the decision-making process and, if you take the position, best of luck and give it all you can.