Lumia 520 and 720 phones getting Cyan update in India

mia Cyan over the air update is rolling out now for the Lumia 520 and Lumia 720 smartphones in India.
This means that those phones will be able to get Microsoft's Windows Phone 8.1 upgrade. As we have mentioned before with previous OTA updates to Windows Phone 8.1, anyone who has the Lumia 720 and 520 and has already downloaded and installed the Developer Preview version needs to downgrade to Windows Phone 8.0 before they download the new over-the-air update to 8.1.
While we were expecting the Lumia 520 to get updated to Cyan this month in India, the update to the 720 is a bit of a surprise as that phone was not scheduled to receive the update until September. The Lumia 1020 has already received the Cyan update in India, while the Cyan downloads for the Lumia 920, 820, 620 and 825 are supposed to be out next month.

I have many paid apps installed on my device and some free promotion apps like wpcentral etc, if I use your method and update my phone to cyan will all of my purchases will be gone or it will be restored, also keep in mind about promotional free apps,... Secondly
I have updated my phone to windows phone 8,1 update 1 to developer preview, there are some bugs in the preview and my phone hangs at times.. Will it be resolved in original cyan update??I have to downgrade really,? No patch available yet?, If this method works fine and if you used it? and of course will all of my settings and app will have no change?And if I update to cyan then can I update my phone further to update 1 by preview for developers? Should I wait? Do cyan have some featured which are not in preview........
Thanx in advance
All others comments are also welcomed.

Unfortunately there is no direct upgrade from Developer preview at this moment. Microsoft has blocked all phones from receiving the upgrade due to a bitlocker issue. The only way to receive the Cyan firmware is to downgrade your phone to the original Windows Phone 8.0
Your personal settings, phone settings, accounts, text messages will automatically saved to the cloud. The only thing you lose is saved game data on your phone or SD card. All your purchases are tied to your Microsoft account. As long as you login with your Microsoft in the last step all your purchases will be restored automatically. All your apps will be automatically downloaded. Make sure you follow step one, its very important that you do an up-to-date backup prior to downgrading.
After you receive your Cyan firmware, you may launch your Developer Preview app, turn it back on and you should get Update 1 with no problems.