I think the first thing to do is sit down and plan out this Civilzation -- its technology, history, and social order, which seems to be the main areas of question. Once it's solid, take look at the story and look when references can be dropped in. Most of the time, additions that add to the reader's understanding of the world can be droped in with a few words, or a sentence or two at most. Info dumps, I think, should only be used for main plot points ("Why is the world going to blow up, Doctor Brain?" "Because they vill be reversing the polarity of ze Neutron flow, and the de planet don't like zhat!")
Most of the BG can be dole out, building up the picture of this world and the people who live on it. And if done right, even the main plot point can be boiled down to a few sentacnes, IF most of the info has already been dealt out earlier in the book, as part of the BG. Say a major polical figure was going to be assasinate (Major plot point), have said politician on the news, or the main character listen to their speech, or discuss the politican between two or more characters, or best yet, use all three ways to give the reader a picture of this person. sprikle a fw referecnes about the character though the first book. So, by the time the Assasination attempt is revealed, there's no need to explain who Politician is or why their important.
Of course, most of my writing has been in an estabished universe that already has all those details hashed out, which leaves me to only worry about plot points and Characters. I don't have to explain what a Battlemech is, or go into great detail about the major interstellar states of the Inner Sphere. So, a lot depends on how much the background influnces the story. I have less freedom with an established universe than I would have with my own, fully created universe.
As I have said, pick your spots to show a little more of the setting, and make sure the background being dropped in is relavent to the scene and story -- mentioning a sport called Quiddich and explaining the rules when it has nothing to do with the main plot is a waste of paper and time. Of course, there's nothing wrong with having a character complain about last night's Quiddich, then have them described enough of the action so the reader knows it involves broomsticks and more than one ball, that's fine. It's color.
Hope that helps -- I'm off to bed!!
Craig