Add support for auto-answer mode when placing calls. We would want to use this judiciously or it could be very annoying.

The main place I see it being useful is when you want to place a call. Instead of it ringing your local phone (and you having to pick up) before placing the call, your speakerphone would pick up immediately and the other phone would start ringing.
Auto-answer isn't a generically implemented feature in Asterisk or phones as far as I can tell. The way people usually implement it is to have a pre-pend to people's extensions. So, if 7777 dials me, 87777 would dial me but auto-pickup. I would suggest we implement the feature this way – allow people to turn it on and then if they do, they specify the pre-pend for auto-answer mode.
action: originate
priority: 1
context: from-sip
channel: SIP/6131
exten: 6134
Variable: ALERT_INFO=ring-answer