The most interesting feature for me ist the Part “Anwendungs-Sperre” (Application-Locking in English?). I would like to have a feature, that App XYZ (Skype, WhatsApp and Others) are not installable via Google Play Store. Or if they are installed on the Device, I can successfully stop Internet access for this Apps. It would be useful, if i could control this behaviour via a Webportal from Remote. Is such a Task possible with avast! Mobile Security? Is this a Premium Feature? Would must i pay for this (its not clear in Google Play Store)?
No, application locking does different thing; the ones you described are not possible to do on most devices /may be on rooted ones/, you can not block Play or installation… For network access control you need to have rooted device - then you can try firewall.