user11495: Does my Bitcoin-Qt wallet backup file have "everything" I need (private key)?
I mean, is that the file I would copy and store offsite in case my house burns down? Does it have my private key encoded in there?

user5406: You only need to copy the wallet.dat to backup your private-keys. Do this while Bitcoin-Qt is not running. All other information will be deduced from the blockchain once you re-import the wallet.dat except any custom labels you have given to addresses.
Of course, if you encrypted the wallet.dat you will also have to remember the passphrase.

user-1: Your bitcoin.dat file contains your private key(s) as well, however I would suggest you extract them now for the addresses that hold money (if any), if empty then it's not much of a use, unless you accept donations there or have a business set up to that address. 
How to extract your private keys for addresses that hold at least some money:

Go to Help > Debug > Console
Unlock your wallet if it is encrypted by calling: walletpassphrase YOURPASSWORD
Call listreceivedbyaddress to get all not-empty addresses
For each of them call the dumpprivkey MYADDRESS
Call walletlock once you're through to lock back your wallet


11495: <p>Does my <a href="https://en.bitcoin.it/wiki/Bitcoin-Qt" rel="nofollow">Bitcoin-Qt</a> wallet backup file have "everything" I need (private key)?</p>

<p>I mean, is that the file I would copy and store offsite in case my house burns down? Does it have my private key encoded in there?</p>
 5406: <p>You only need to copy the <code>wallet.dat</code> to backup your private-keys. Do this while Bitcoin-Qt is <em>not running</em>. All other information will be deduced from the blockchain once you re-import the <code>wallet.dat</code> except any custom labels you have given to addresses.</p>

<p>Of course, if you encrypted the <code>wallet.dat</code> you will also have to remember the passphrase.</p>
 -1: <p>Your bitcoin.dat file contains your private key(s) as well, however I would suggest you extract them now for the addresses that hold money (if any), if empty then it's not much of a use, unless you accept donations there or have a business set up to that address. </p>

<p>How to extract your private keys for addresses that hold at least some money:</p>

<ol>
<li>Go to Help > Debug > Console</li>
<li>Unlock your wallet if it is encrypted by calling: walletpassphrase YOURPASSWORD</li>
<li>Call listreceivedbyaddress to get all not-empty addresses</li>
<li>For each of them call the dumpprivkey MYADDRESS</li>
<li>Call walletlock once you're through to lock back your wallet</li>
</ol>
