diablo-3
How do Diablo 3 updates work?
I was just playing, and read on a forum that there was an update, so I restarted the game and it began updating, my question is, if I never close the game, do I never get the updates?
What happens then to multiplayer games? Only players who haven't updated can play games together? Or how does that work exactly? Because I was never kicked out of battle.net (like I was used to in retail Starcraft a good 10 years ago)
To answer your questions directly:
You can only create a character starting on Normal difficulty. You'll have to defeat all 4 act bosses and complete the Prime Evil quest on Normal difficulty to go to Nightmare and play with your friend who is on Nightmare, and you'll have to redo this process for any character you create. This follows for other difficulties as well. Edit: There are now level restrictions: you must be 25 to advance to Nightmare, 50 to advance to Hell, and 60 to advance to Inferno.
You must be online when playing Diablo 3, so you can join your friends whenever you want. You can join a friend's game without invitation unless it is private. If it is private, message them asking for an invite.
If your friend just buys the game you can join him in his quests, but he cannot join you until he has unlocked the difficulty you are playing on.
One important thing to note is that the only restriction for friend joining you is that they have unlocked the difficulty you are playing on. Unlocking quests doesn't matter; only unlocking the difficulty does.
So if you want your friend to play with you, change your quest to a quest on their difficulty. Note that this doesn't mess up your save file or anything; you will be able to return to your previous quest and difficulty after you've played with your friend.
First click the Change Quest button in the main menu (notice I am currently on Hell difficulty):
Then select Normal Difficulty from the drop list:
And finally select the any quest (here I select Prime Evil) and click the Select Quest button:
Note the warning: the only drawback to this is you lose all progress for your current quest. So finish up what you were doing before switching your quests!
After clicking OK, then you should notice your current quest change in the main menu:
And now when you start the game your friend can join you.
I've done this with my friend to skip the Butcher on Hell difficulty, mostly because I wasn't geared to fight him toe-to-toe. Proof is here that joining your friends can help you skip bosses (I skipped Butcher but killed Belial):
However, to advance to the next difficulty you will have to defeat all four act bosses.
Alright, you CANT change the binding of the move/primary/interact and secondary attack (fixed as left and right mouse click). But you can define the action bar buttons as you like - also mouse wheel works.
Key Bindings Overview 
See Actionbar at the bottom, the first 4 buttons refer to Action Bar Skill 1-4 and the last two are the Left and Right Mouseclick (as indicated by the symbol)
You have to enable Elective Mode to be able to place skills wherever you want to, else they are restricted to categories (good for newbies so they always have a somewhat decent skill set active)
Best Answer
The update you just downloaded was not to the game itself, but rather to the Diablo III Launcher. Because the Launcher update has no actual impact on gameplay, it can get pushed out at any time, and it does not matter whether your friends have updated it.
Other gameplay updates will come in the form of either Patches or Hotfixes.
Hotfixes will be announced on the Diablo Website or forums (sometime a few hours or days after the fact), and are applied server side. These do not require you to download anything, and your gameplay experience will reflect the changes immediately. Occasionally, these hotfixes require Blizzard to restart the games servers, either momentarily, or for an extended period. Either way, everyone is up to date because all of the changes are server side.
Patches will generally only occur in conjunction with announced server restarts or downtime. You will not be able to connect to the game with an out of date client, and before the patch goes live, you will be disconnected, as the servers go offline for Blizzard to apply their side of the patch. If you never close the game, you won't get the updates, but, since you'll have been disconnected, you also won't be able to log back in - after the update goes live, your attempts to connect to the server will be rejected until you update to the newest client software.