You have asked several questions:

1) 40 year old celebrity photos. - I suppose you are talking about the age of the photos and not the age of the celebrities. In answer to that, here is what the Copyright Office says:

"How long does a copyright last?

The term of copyright for a particular work depends on several factors, including whether it has been published, and, if so, the date of first publication. As a general rule, for works created after January 1, 1978, copyright protection lasts for the life of the author plus an additional 70 years. For an anonymous work, a pseudonymous work, or a work made for hire, the copyright endures for a term of 95 years from the year of its first publication or a term of 120 years from the year of its creation, whichever expires first. For works first published prior to 1978, the term will vary depending on several factors. To determine the length of copyright protection for a particular work, consult chapter 3 of the Copyright Act (title 17 of the United States Code). More information on the term of copyright can be found in Circular 15a, Duration of Copyright, and Circular 1, Copyright Basics."

So, more facts are needed to answer your question, although the above will tell you the answer is that it may be an infringement.

2, No, use of the name is not a copyright infringement, BUT it may well be Trademark or Service Mark infringement depending on how you "use" the celebrity's name. If you put it on merchandise and sell the merchandise, you are very likely to be infringing and are likely to get caught as that is where celebrities and their estates make the really BIG money and that is what they police carefully and aggressively.

3. Yes, copyright infringement and trademark infringement of a celebrity's image and name can occur long after the celebrity dies. As noted in the response to question 1 above, for 70 years after the author of the photograph (generally the media company hiring the photographer or the photographer himself or the celebrity) dies, the photo is still subject to copyright. Trademarks last forever if continuously used and registered.

Celebrity rights outlive the celebrity. "The King of Rock", Elvis, has been worth more dead than alive. The same will likely be true of MJ, "The Prince of Pop".