Open ImgBurn, look in the log for a line similar to this
2. Taiyo Yuden
3. You got that error because the target was set to a DVD 9 and ImgBurn can't find any cells, that can be used for the layer-break point. Did you read that Guide I linked?
I think there is no reason to make an avi to fit a DVD 9, you can safely use a DVD 5 with almost any noticeable quality loss and save your money.
Make your project in two steps, first encoding than the burn. To do that, untick Burn project to disc in DVD Flick Project Settings/Burning
4. Yes
Yeah I read the guide. I used DVD Flick though, not Imgburn