So Many Copyright Questions ... So Little Time

Dear Rich: (1) What is the length of time the U.S. Copyright Office takes to approve or not approve a copyright application? (2) If I secure a lyrics copyright on a public domain melody for commercial purposes can someone else use that same melody with different lyrics --- say a competitor -- and secure another lyric copyright on that same melody? (3) Regarding the renewal of copyrights, is a renewal of copyright application sent out to copyright owners at the appropriate renewal time, by the copyright office or is there a formal time frame that copyright owners must adhere to? How many times or how often is that renewal required? (4) When using public domain music, it is difficult for me to not have a doubt the melody could have copyright protection. Does using a disclaimer provide some helpful consideration in the case of an infringement? Does using a disclaimer absolve the defendant from fines if the cease and desist notices are honored and observed? (5) If a request for a copyright on an established (for sure) melody in public domain has not been approved or affirmed by the copyright office, and an opportunity to negotiate a deal for that completed song arises, what are the risks if the business is carried out despite the fact the copyright and request had not been confirmed? We'll go through your questions, below, but first we wanted to remind you that copyrights are not like patents or trademarks for which "approval" by federal government examiners is essential for protection. Copyright is automatic and registration is necessary only if you want to sue an infringer. Here are your answers by number:
(1) It takes three to five months for an electronic copyright application to be processed. It can be expedited if you are suing someone.
(2) Yes, anyone can receive copyright protection by creating lyrics for a public domain melody (ask Elvis).
(3) Copyrights no longer have to be renewed. Renewal obligations ended for works created after 1963.
(4) Music is either in the public domain or not. If you need help determining public domain status, consult this website or use this book. A disclaimer may have some effect in a trademark infringement case but a copyright disclaimer -- especially the meaningless and confusing use of "No copyright intended" -- has little to no effect mitigating copyright infringement. 
(5) You can't acquire copyright protection over a public domain melody. You can only acquire protection for original material that you add to the melody, or for the manner in which you creatively re-construct the melody.