I am not an IPCC expert so hopefully someone else can address item 1.
2. If you are referring to Extension Mobility and IPCC together, then the answer is that it has not yet been fully tested and this will be done. As far as I know there should be no issues.
3. Q.SIG will be supported by CallManager sometime next year, and it will be implemented in a phased approach. The particular function of Path Replacement as it is referred to in Q.SIG will be supported. I can say that this is being worked on right now but I can't give an exact timeframe on when it will be available and in which CallManager version.
Are you getting this error “Installer User Interface Mode Not Supported. The installer cannot run in this UI mode. To specify the interface mode, use the -i command-line option, followed by the UI mode identifier. The value UI mode identifiers...
The below trick might come handy when you have to add a new node to a cluster but you don't have or is unsure of the security password for the publisher. This procedure has been around for ages.
1) Login into the CLI of the Publisher.