Developing to all devices

Is there any way with the Android SDK to emulate a specific device ROM? For exampl开发者_如何转开发e, could I launch an emulator that replicated the Verizon Droid Incredible, or the Sprint HTC Hero?

There is not a way to say make my emulator be a Droid. However, you can create an avd with many of the features of the different phones: sdk versions, screen sizes, disk space, etc. See avd documentation for details. For most applications, as long as you test against a few different sdk levels and screen sizes you should be ok.