In General
Addictions are something that are difficult to handle without rules support, because they tend to deal with something that is both outside your character's control, and completely alien to many players.
The key to roleplaying an addiction is to understand that your character is fundamentally not rational. The addiction is effectively attacking the decision centers of the character's brain, and elevating its own importance.
What you need to do, is imagine that keeping current with the drug has some reward attached to it... The more serious the addiction, the larger the reward.
The kinds of questions you need to be asking yourself are:
Would you leave your post for a million dollars?
Would you leave your post to save the life of a loved one?
Would you take a small penalty on the next adventure in exchange for more experience?
Clearly, the answer won't always be yes. The trick is getting the scale of the reward right... And to have the discipline to evaluate the decision as though your character were actually getting the reward (even though they aren't). Rules support helps with this quite a bit in many systems.
As Acedrummer notes, there are a number of potential pitfalls to the situation:
Don't be addicted to something so nasty that you'll become a major liability to the party (unless your group is really into that sort of thing). This is a general good practice: Don't put yourself at direct odds with your group. Annoying them can work, but don't take it beyond that.
Be aware of how optimally people at the table expect eachother to play. You are essentially playing poorly for the sake of the experience... Make sure that you have the right group for that.
Overcoming the addiction
So far as I'm concerned, this is something that should be handled primarily in-system. It has a lot to do with factors outside your character's control (their willpower, availability of help, supporting environment, and so on). Treat it like you would combat: make the roll, and then roleplay around the result.
The main point to note here is that, again, your character probably doesn't really WANT to kick the habit (even if they do). It can be treated as a tradeoff between the benefits of kicking the habit and some fictional reward, if you have the discipline to pull that off (it's harder than it sounds).
Also, if you received points for taking the addiction, you should generally repay them upon kicking the habit.
The GM takes on more work than any individual player in making the world and the game come to life. Obviously a GM without players has nothing, but the lynchpin of the game is still the GM. Having played in many games and GMed many more, I come into any game with the understanding that because the GM has to do so much work just to get the game going, that person should be given the benefit of the doubt where possible.
Your player's reaction to me seems a bit off, in that you were just getting back into GMing and this was the first session in a new campaign. To expect everyone's expectations to align perfectly, and the session to play out without corrections or adjustment is asking quite a lot.
For detailed background, I generally provide overview text and invite the players to ask questions as they come up. It's perfectly acceptable for a player to say, "I figure these thugs should be licking my boots because I'm a member of the guard. Is that right?" This approach requires that the GM be able to fill in details on the fly, but it also puts some of the responsibility on the players. Some players may bristle at this approach because they find it too meta, but the necessity of using it fades away as the campaign develops and the players become more immersed in the world.
Best Answer
Back in the day, and today available as a PDF on the web somewhere, is Paul Jaquays' Central Casting: Heroes of Legend.
I highly recommend it when you just don't want to conjure something anew, or just need hints to spark the conjuring fires. My most recent Pathfinder ranger was built using HoL and I had a lot of fun using the book. It even has charts for developing flaws based on your attributes/characteristics (or even using the charts to instead "develop" attributes from events in the characters life).
More recently, Masks: 1000 Memorable NPCs for Any Roleplaying Game from Engine Publishing is now available. There are three genres covered: fantasy, modern, and sci-fi. While ostensibly a NPC tome, the authors have crafted a valuable book for getting ideas for memorable characters as well.