Hi! Can I use any Android Phone for app development? Here in the Philippines, there are many available mobile phones with Android installed. But I want to buy the cheapest phone available (which I think is Samsung i5500 Galaxy 5). Thanks in advance!
Why not use the actual dev kit? There is a complete setup with virtual phone included that you can run as an eclipse plugin.
You can use any android powered device for development, just make sure it has Development menu option. To check go to Menu -> Settings -> Applications -> Development. If there is somewhat like USB Debugging option you can use device for the development.
Yes you can, and I would definitely recommend using a real phone. The emulator is excellent, but somewhat slow for a number of applications that require hardware (OpenGL comes to mind). Even a G1 tends to be faster than the emulator for certain things. If you're creating an app that uses Bluetooth, there's no way to do so on the emulator currently. Konstantin's directions are good for actually setting up the phone.
You need to understand one thing before you buy the phone. What version of Android SDK you will be using for to develop the app. If say, you are developing the app for cupcake and above, you better have a phone with cupcake version. But if you have Froyo phone, you will not be still able to run the app, but some depreciated functions might not be available and your app may crash.
If you want to develop in Windows there is a list of devices available for which the USB drivers work: USB Driver for Windows
If you don't need the GSM part you could also think about using the Archos 5 Internet Tablet, which is a Android powered media player and supports ADB (Android debug bridge) as well