I don't think this configuration has ever been tested here, so I can't say anything for sure, but:
1. The managed clients are basically identical to avast! Professional - only they can be controled by ADNM. The skin-less Simple User Interface, for example, should work with screen-readers without much troubles.
2. The idea of the managed clients is that the antivirus runs in background, without user intervention. The updates are automatic, automated action for infected files are defined (well, I don't know exactly what the default setting is, but it certainly can be configured) - so the user shouldn't be required to do anything.