You might want to talk to a sales guy for more in depth information but:
Latest version - They're agent specific so you can see the latest versions of the different agents here: https://download.appdynamics.com/download/ although generally the latest release for most things is version 4.5, the docs for that are here: https://docs.appdynamics.com/display/PRO45/AppDynamics+Essentials
OS - Same as the download link above can give you an idea of which OS' the different agents work on, but the Console/Controllers I think typically use Linux or Windows.
Components - Same download link as above can help you get an idea of all the different components, there are a handful of different agents, each with their own unique metrics they report in.
HA/DR - I utilize an On-Premises solution, so we have our own DR procedures, but they offer a SAAS solution which I imagine has the standard stuff.
Flavors - Yep, there is SAAS or On-Prem, you can also go Hybrid if you want to keep some agents On-Prem, while others in the cloud for Synthethic heartbeat/script monitoring.
