===What application should I use for reading Barcode and QR-codes? ===
Use the [https://play.google.com/store/apps/details?id=com.google.zxing.client.android Barcode Scanner] application from ZXing Team.
On the Getac Z710, a barcode scanning app might be already installed, if the device has a dedicated barcode scanning module.
===What application should I use for editing picture documents? ===
Use an application fitting all requirements is [https://play.google.com/store/apps/details?id=com.aviary.android.feather Photo Editor by Aviary].