Q: i can't boot bootcamp

After you download the ISO file to you Mac, run Bootcamp Assistant. BA look sat the Mac model, and shows you this screen.

Check both boxes and put a USB in the MBA. It will prompt you for the location of the Windows ISO, partition the disk, reboot and start the Windows installer. The second check box will down Bootcamp drivers 5.1.5640 from Apple's website.

From http://support.apple.com/kb/HT5639

Can I use a downloaded (ISO) version of Windows with Boot Camp?

MacBook Air (Mid 2011 and later), MacBook Pro (Mid 2012 and later, including Retina models), Mac mini (Mid 2011 and later), and iMac (Late 2012) can install downloaded (ISO) versions of Windows 7 and 8.

If you can use an ethernet connection, the download will go faster. The other advantage of downloading is that the Windows installation also installs the Bootcamp drivers without prompting. You can use the same USB which currently has the drivers. You will need a 8GB or 16GB USB2 flash drive.

1. Create a new folder on the MBA under Documents, say luis098765.

2. Copy everything from the current USB which has Bootcamp drivers to this directory.

3. Run BA which will erase and format the USB and use only the first check box.

4. Once the USB is built, copy all the data from luis098765 folder back to the USB.

5. You will need to run the setup.exe from USB under the Bootcamp directory once windows is installed from the USB. You may run into issues where you keyboard/mouse/graphics may not work. If they worked during the original install when you did not have the correct drivers, then it should work using the default drivers  which the Windows DVD already has.

1. In disk utility, click on disk0s4. Click on the '-' sign.

2. You can put the ISO anywhere,.

BA will erase/reformat but you should make it MSDOS, but it already should be.

Can you post the output of diskutil list?

In OSX Terminal type diskutil list. Highlight it by holding the mouse button down and dragging till you get to the end of the diskutil output. Type Command+C and then paste it in the reply window using Command+V.

It may actually be easier if you run sudo gpt -vv -r show /dev/disk0  and post its output.