Well, the books took place in the 50's and 60's so he would have been in his 30's and maybe early 40's for historical settings. Obviously they are going to update the character for modern times.

After Fleming's death there were several books written by other authors. Some took on the air of the Roger Moore films, others were more along the lines of Fleming's style.

One book by John Pearson, that is long out of print and rarely discussed, was called "James Bond: The Authorized Biography". The book was about a writer meeting with Bond, who was forced into retirement, to discuss writing a biography of his career. The premise was that Bond was "outed" by Ian Fleming in a series of books after the Russians attempted to assassinate him. "M" decided to turn Bond into fiction and had Fleming write accounts of the real adventures in an attempt to confuse the enemy. (Don't ask - it was strange, but it worked well enough in the book.) The book has Bond reluctantly talking about his "real" history - including his early days in WWII.   It ends with Bond being asked back into the service - supposedly with another story.   What was interesting about the book is that it took a number of "clues" and events from Fleming's books and made sense of it all.

Bond has become a part of folklore, and I hope the series of films - and books, will continue for a long time.