The alarm could be due to a faulty door switch. Try using the passenger door to unlock to test if problem persists.
Surging idle can be due to various causes and one of it is excessive low idling whereby the engine computer would try to compensate and increases the idling rpm. It would then reduce when it finds the idling rpm is too high.
There are other possible causes and you need to hve it checked to find out what is causing it.