I am trying to install the Android SDK 2.3.3. using the Manager. I have selected all packages, yet some egregiously demand login information, e.g. Open Sense demands a login on htcdev.com, same with the Motorola packages, only it’s a different site there.
Hence my question: Is it necessary to install those packages to start developing for Android? Does it work without? What would be the downside of not using those packages?
No they just contain some custom AVD emulators. You´re fine without them!
If you want to test on an emulator you can create one with just a few clicks.