The documentation for API 7 includes the documentation for all previous versions. It's just an offline copy of the Android Developer website. Just as you can see there, next to every method and class in the 'reference' section there's a note saying "Since API x", telling you when it became available.
By the way, and this is my personal opinion only, but there isn't much point in developing for v1.6. As you can see from the official statistics, one third of devices are still running v1.5. It's better to use the trick described here about settings the minimum SDK version to 3, yet targetting SDK 4 to allow you to support multiple screens but ensure compatibility with all versions.