- UPDATE: As of now (2013), the rumors are that there will be an ID4:2 sequel, sans Will Smith but with Pullman/Goldblum. Since it won't be out till 2015, we don't yet know how canonical it will be.
First of all, there was a tie-in novel/novelization. It did offer more information/details than the movie.
There was a prequel book about Dr. Okun (Independence Day: Silent Zone)
The same author who wrote a prequel had written a midquel/sequel novel Independence Day: War in the Desert
There was also a computer game. It probably (like all games) had some extra details/backstory but I'm not aware of anything earth-shattering it added information-wise to the franchise
As far as sequels:
The possibility of a sequel had long been discussed, and Devlin once stated the world's reaction to the September 11 attacks influenced him to strongly consider making a sequel to the film. Devlin began writing an outline for a script with Emmerich, but in May 2004, Emmerich said he and Devlin had attempted to "figure out a way how to continue the story", but that this ultimately did not work, and the pair abandoned the idea.
In October 2009, Emmerich said he once again had plans for a sequel, and has since considered the idea of making two sequels to form a trilogy.
Also, further info not yet on the Wiki:
"Independence Day 2 is nowhere. It’s back and forth, back and forth. There’s no script because I don’t want to write anything before anything starts," said Emmerich, although he did confirm the following, "One day it will happen."
Looks like sequel film is back on track (Wikipedia as of 2/10/2015)
On November 12, 2013, it was announced that the first sequel had been rescheduled for a July 1, 2016 release. On May 29, 2014, it was announced that the script for the first sequel written by Emmerich and Devlin, would be rewritten by Carter Blanchard. On October 14, 2014, Fox moved up the release date to June 24, 2016. On November 26, 2014, the sequel was given an official green light by 20th Century Fox with a release date of July 4, 2016, noting that this will be a stand-alone sequel that will not split into two parts as originally planned, with filming beginning in May 2015 and casting being done after the studio locks down Emmerich as the director on the film. On December 4, 2014, Devlin confirmed that Emmerich would indeed be directing the sequel. On January 27, 2015, The Wrap reports that Liam Hemsworth is being eyed for a role in the sequel.