How to start another book in a series.

That is one thing I have been having a problem with lately.  I know I am not completely done with my current book, editing wise.  But Its camp Nano month during July and I am using the time to get a head start for my Nov Novel.  Last year I had already written 40,000 words before Nano, tacked on another 50,000 because of Nano and then wrote another 10,000 worth to finish the book entirely.  So this year I am thinking that if I can a head start, I can get it done sooner this year, or have to do less after November. 

However, I am at a loss and would greatly appreciate ideas from anyone on how to start a second book to the series.  I already have an idea of how to start it, starting from an un answered question from the first book I purposefully left open to bring into the second book. 
Here's the catch though.  As a writer you are supposed to portray a number of things on the first page or first couple of paragraphs of the book to set the stage and intrigue the interest of the reader. 
Do I still have to do that with the second book in a series.  Or can it just portray the main characters and only one part of the plot of the book.  I believe it should still be within the first 5-10 pages or first chapter that any new characters be introduced.  But that's just it.  My new character is the new plot but I cant introduce him on the first page let alone the second.  

So here is my question I direct at you to please comment with your answer.  If its the second book in a series, and you have or haven't read the first but you at least know it is not the first book, do you expect there to be everything laid out on the first page and a half?
Or, because of the fact that you know that it isn't the first book, you expect to find out things a little bit later because the characters were already laid out in the first book, so you just have to get to know the new characters and new plot structure. 

Your comments would be greatly appreciated.  Thanks for your help.
Destiny.