Is there any way to limit my iOS app be available for Gen 2 iPads or better and iPhone 4 or better in the app store? I can do this in Android so I imagine their is an iOS equivalent.
You can't restrict your app to specific devices, but you can configure it to require certain hardware features by including the UIRequiredDeviceCapabilities key in your Info.plist.
This is an array of strings, you can find details about which keys are available in the iOS Application Programming Guide.
By including "front-facing-camera", for example, you would essentially restrict your app to iPhone 4, iPad 2 and latest-gen iPod touch.