Are there any known incidents of ejections by capsule? What are the survival chances?
While the F-111 had a custom build escape capsule integrated with the cockpit, escape capsule designs have been used in the past.  One notable type was the Stanley Corp. Ejection Capsule.  It was a special type of ejection seat which used a pressurized clamshell-type enclosure which could be deployed rapidly once the ejection process had been initiated.  It was designed specifically to protect a pilot against a supersonic, high altitude ejection which would have almost certainly been fatal using a conventional ejection seat.  The system was used on both the B-58 and XB-70 aircraft.


                
            

The system was pressurized allowing a flight crew to use standard life support equipment as opposed to a full body pressure suit for high altitude flight.

One notable ejection involving the Stanley capsules was the loss of XB-70 prototype No 2 on 8 June, 1966 near Barstow, CA.  During a formation flight of several other aircraft with the XB-70 for a General Electric photo shoot, an NF-104 collided with the starboard wing and tailfin of the XB-70 and disintegrated in flames, killing NASA test pilot Joe Walker in the process.  The Valkyrie continued on straight and level, then waltzed out of control and began tumbling toward the desert, spilling plumes of fuel vapor as it went.  Commander Al White initiated the ejection process using his Stanley capsule and egressed the aircraft but was seriously injured by failing to clear his arm from the clamshell enclosure during deployment.  The copilot, Carl Cross, failed to initiate ejection and rode the crippled Valkyrie to the desert floor, killing him in the process.