1. Border and padding are specified in pixels, and are pretty straightforward, unlike the inner/outer values.
2. MarkAsChanged() is used everywhere now instead of a mix of MarkAsDirty / MarkAsChanged.
3. Yup.
4. There was a post about it with in the 3.0 days... I think it's still linked to from the version notes thread in the 3.0 post.