You probably don’t have write access to the folder you’re trying to create the keystore in.
In fact it looks like you are in the Java bin directory which is probably write protected from non-admin users. You can either CD to a directory where you have write access, like your desktop, documents directory or the projects folder where your project lives and then execute the command to generate the keystore from there. Or if you feel you have to run it from the bin directory, specify a path in front of the keystore name that will put it in one of those writable directories.
Regarding Android Icons. Corona SDK has only recently started supporting the Icon-xhdpi.png icon, but the latest Stable build (971) should have it, the previous stable (840) does not. The Android icons are:
Icon-ldpi.png 36x36
Icon-mdpi.png 48x48
Icon-hdpi.png 64x64
Icon-xhdpi.png 96x96
http://developer.android.com/guide/practices/ui_guidelines/icon_design_launcher.html [import]uid: 199310 topic_id: 8963 reply_id: 135319[/import]