Hi Zaeem,
From what I understand (and wat's left in my memory), my answer to your questions:
1. It will depends heavily on your download speed.
- First you'll need to download the latest NSU (20MB).
- After running NSU, it will detect your type of mobile and your operator.
- Next, it will download the appropriate firmware image for your mobile and operator (nearly 80MB for my N80).
- The actual update itself took about 5 minutes.
2. Unknown. From what Nokia told me, by design, NSU will place the new firmware on another sector of the phone memory. So, if the update fails, it will just revert back to the existing firmware; if successful, the new firmware would then replace the existing at initial successful boot up. But having said that, Nokia wasn't willing to put a commitment that it is totally 100% safe.
3. My own list as follows ->
- Ensure that your mobile is fully charged. We wouldn't want the update to fail because the mobile ran out of battery.
- Backup your mobile, either to your MMC or PC. Personally, I do both.
- Synchronise the content of your mobile. (I realised by chance that somehow, the backup doesn't backup or restore every information.)
Note that some stuffs like security settings like PIN code will be set back to default. So remember to change them back.
Hope this helps.
Cheers. ^_^