You don't need to perform point 4 at all
All you need to do is generate and PRINT on paper your private key (Help > Debug window > Console > dumpprivkey your_wallet_address)
If you have private key you can restore later OFFLINE your current wallet.dat file on any PC or Mac computer
Here is how:
Sync with the network without your wallet.dat
Switch off internet connection and quit Bitcoin-qt
Import wallet.dat with BTC on it
If you don't have your wallet.dat file you can recreate it now: Run Bitcoin-qt and then click: Help > Debug window > Console > importprivkey your_wallet_private_key (it take a while because Bitcoin-qt must scan over 14 GB data (on my PC about half hour)) and then quit Bitcoin-qt
Run Bitcoin-qt so your wallet will be updated
Enter destination address and BTC value you want to send
Switch on your internet connection and then click send button (so even if you have any malware or spy program on your computer it's impossible to steal your BTC because attacker have only few seconds when wallet.dat file with BTC on it is online)
NOTE: as a rule of thumb I always send all BTC from my current wallet.dat file and NEVER use it again
Check on https://blockchain.info/address/your_wallet_address if your BTC was send and wait for 1 confirmation (if you give a tip it takes about 10 minutes, without tip about one hour)
Switch off internet connection
You don't need to save your wallet.dat after step 9
You can restore later your current wallet.dat on ANY computer offline performing steps 1, 2 and 4 above)
Of course if you have a loot of BTC on ONE address it's smart move to split it on 10 different addressees
So even if something going wrong you lost only 10% of your BTC
Summary:
Generate 10 (or 100) new BTC addressees on offline computer with Bitcoin-qt only (with fresh Windows, Linux or Mac OS install) - click: Receive and then 10 or 100 times click: +New Address
Copy to TXT file all above addresses
Generate and print for each BTC address private key (Help > Debug window > Console > dumpprivkey your_wallet_address)
Delete wallet.dat file
Restart or switch off your computer
Of course made 2 or more hard copy with printed private keys and store in 2 or more save places