I have 12 years of experience in voip field.
I have been working with Asterisk PBX since last 11 years from version 1.2 to till the latest version.
I have developed many projects based on asterisk like IVRS, Billing module, Autodialer, Voicemail system, Conference system, Call center solution (Highly availibility/Traffic) , Multiple office setup, Voice/Video switch, Multiple Asterisk PBX integration with other Switch like Opensips, Freeswitch.
I have developed various system using AGI(Fast agi, Dead agi), AMI, ARI and more.
I have also installed Asterisk and required packages on various VPS / Cloud system with various linux based OS like Ubuntu, CentOS, Debian, Redhat.
Based on your link I can make your setup successful by using FAST AGI with HA Cluster.