OP, if only it was a case of losing your no claims bonus than you would have little to worry about. Generally speaking, with many motor insurance policies theft of the vehicle will not affect your no claims bonus.
However, theft of the vehicle with the keys in the ignition (as I assume happened here?) is a different matter entirely. Most insurers operate on the basis that loss or damage caused by theft or attempted theft if the keys (or keyless entry system) are left unsecured or left in or on an unattended car are not covered. So in all probability the damage to your own vehicle will not be covered and you will have to make good this damage yourself.
In regards to whether you iwill bear the responsibility for the loss/damage caused to the other vehicle/driver it will depend on the specific circumstances of the case. A relatively recent Supreme Court decision (Breslin -v- Corcoran) in a similar case did not find the driver who left his keys in the ignition liable for the damage/injury caused to a pedestrian as a result of a collision, but it must be remembered that all these cases turn on their own particular facts; accordingly, this should not be interpreted as a definitive view. Nonetheless, I would have thought that the other driver should be able to recover from the Motor Insurance Bureau of Ireland (MIBI) pursuant to the relevant Agreement.