Program different layouts for different versions in android

Question

I have to program my Android app with the best compatibility to different screen sizes (tablets and smartphones) and to the versions 2.3, 3.2 and 4.0. I know about the possibliy to name the folders of the layout like res/layout-sw600dp/. to match the layout exactly to different screen sizes.

So, cause I will use completely different layouts for Tablets / Smartphones, I would start with a "Load Screen", which tests which Android-version is used and if there is used a tablet-or smartphone-device, cause for example in the layout for the Tablet, there will be Buttons on some screens that won't be there on the smartphone.

So I will have to separate all this in packages, like this:

• Common
• 2.3
  • Tablet
  • Smartphone
• 3.2
  • Tablet
  • Smartphone
• 4.0
  • Tablet
  • Smartphone

I would choose this separation, cause it's the best way, in my opinion, to be prepared for upcoming *updates*, if, let's say there should be added a Button in the ToolBar in Android 4.0.

Is this separation a good thing in your opinion or is this a complete overload?

Are there any other new features in 4.0 that I should be aware of?