OK so your idle should be 700 +/_50 and 2100 +/_200 as to the gearbox, just drain it and refill then with the engine running manually select each gear a couple of times then stop and check/adjust oil level then give it a test drive.
Not sure on the gearbox on your car but on some auto's there is an oil filter in the bottom of the box that need to be replaced at regular intervals as well, normall this will involve dropping the sump pan off the g/box
nigel
December 2011