We found a small external head gasket leak on the front left side on my impreza. I have jumped on it early, and have a fair amount of cash to invest into it.. What else should I replace? Any advice for the repair itself?

Timing belt, water pump and pulleys done about 4k ago...

5speed manual 2.5 non-turbo.

It is cold outside and the sound goes away after the car has warmed up but it is concerning.

The ticking occurs with both a warm or cold engine.

Car makes a clicking noise in front end when making slow turns. I was told it might be the axle boot but not sure why a torn boot would cause a clicking noise. Car has 150000 miles on it

appreciate any special instructions how to replace this bulb? thanks