The black wire with the red sleeve is Switched Live to turn the light on and off - it comes from the switch - the fan needs to know when the light is on so switched live should be routed to the fan as a "please start up" control signal.
The fan will also need live & neutral to run - and they normally run-on after the light is switched off.
The way you describe the wires for the original light appears to be the normal arrangement.
The light does not connect to the live terminal - it is across switched live (black+red) and neutral (black).
The reason for the Three Connectors with only two being used is that ceiling roses usually loop on to the next rose - i.e. to run a looping cable to another ceiling rose the third holes are used up.
The circuit breaker is tripping because you have made a wiring error - you have somehow connected live to neutral with no load between them.
Get the light working properly then think about adding in the fan - will need 3 wires - do not be tempted to use the earth conductor in the cables for anything other than earth.
See this diagram -
http://www.diydoctor.org.uk/project_images/electrical_safety/ceiling_rose.jpg
consider an electrician if it's all too much for you...
Good luck...
Peccavi
July 2010