Here are the answers to your questions:
1. The name mentioned on the cover letter is correct. Dr. Jeremy Berg is the currecnt EiC of Science. I think you should use the name provided rather than 'Dear Editor' as the former sounds more professional.
2. Science has a very clear tutorial explaining the submission process and the documents required at the time of submission. You can access the tutorial from here. (Click on the hypelink at the end of the first point on the bulletted list.)
The License to Publish, Authorship Form, and Statement of Conflicts of Interest are not among the documents required at the time of submission. The website states that: "In general, authors will complete the license form as a 'click-through' during the process of uploading the revised manuscript after peer review." It also mentions that "For manuscripts that are accepted, all authors are required to affirm and explain their contribution to the manuscript, agree to the conditions of publication including the availability of data and materials, and declare any conflicts of interest."
Thus, it is quite clear that you don't have to submit any of these documents at the time of manuscript submission.