Here’s a link to a couple articles on the Corona web site about making apps to fit a wide range of screen sizes. Be sure to comments there’s a lot of good questions and answers there. The second articles takes the whole concept to a very elegant solution.
The Accelerometer is built into all IOS and other handheld devices, it detects motion of the device, tilting or shaking. Corona handles this with the Accelerometer event.
The accelerometer is difficult to test with, since the Accelerometer events are not available in the simulator. This means that you need to build your project each time you want to test. Which tedious and slow. There’s a solution!
There are several apps that can be used to send accelerometer and other events from a real device to the simulator.
All of these apps are very similar. You install them on a device: iPhone, iPad, iPod Touch etc. Launch and Configure the app. Set up your Corona project to receive data from the device. This consists of adding a few lines of code to your main.lua file.