from somebody who, in a previous life, was involved in corporate hiring:
1) i agree that it is far better to address the hr manager by name. but what are the chances you will get a name from them? you have better odds winning the state lottery. so don't fret about it. hr managers understand that. dear sir or madam will do just fine.
2) drop all bls, acls, ekg, clinical, education and related references. this information is already on your resume and/or online application right? no need to repeat it here. cover letters are not supposed to be a summary of your resume. why would you submitt two documents with essentially the same information? there is a reason why hr wants a cover letter in addition to resume, and that is to give you a chance to convey information not on your resume. don't waste this opportunity. talk about your career objectives, your passions, why you chose to be a nurse, and, most important of all, why you are interested in that particular hospital and in that position. incorporate the hospital's mission statement here. state that you believe and identify yourself with their mission statement. go further and state what their mission statement means to you and how would you apply it in your day to day work if you were selected. give specific examples. but keep in mind that this is a much harder cover letter to write. the temptation is just to summarize your resume, make your cover letter a mini-resume, and this is what 95% of the applicants will do. but once hr managers start reading about bls, acls, ekg on your cover letter, they will put it aside and go directly to your resume. they are ultra busy and will resent you making them read twice the same information. don't miss the chance to make your application stand out from the majority of other applicants. good luck!