It seems you lack of Support libraries which are providing some support for older APIs.

You can find them in: SDK Manager > Extras > Android Support Library

Also you should try-catch string parsing unless you are 100% it's parsable

Check Data Storage section. Your errors says file is not found so that's it. Either is not there or you point to it incorrectly

For the device, any that is able to run Android 2.2+ will do as those versions are currently most popular. Personally i treat 2.2 as "base".

Google Play is the only place to publish apps. Sure you can provide some other way of publishing your app but it will be "hackish" because than user needs to check "Unknown sourced" in settings and it all becomes so 'unofficial'.

Android users like Google Play, it's one place to get anything that's out there and it's not some illegal/suspicious stuff.

You could take a look at ViewSwitcher or something similar.