Caulking exterior windows

I tend to caulk only areas where water is likely to penetrate, as if you do indiscriminate caulking, you can cause water to be trapped where it would normally drain out after a rain, such as the seam/crack just below a lower window sill. The upper drip edge should be a Z shaped galv. strip. If it is, then water should not leak in there. If there are no stains or swelling of wallboard on the inside of the window frame, from prior storms, you are probably ok without caulk on the outside.

Should the gap above the metal drip edge at the top of the window also be caulked?

Possibly, those windows are 55 years old. Might the drip edge succumb to corrosion?

Does the metal part start under the siding then over the top of the window? I suggest not caulking IF the metal extends up under the siding. That allows any water behind the siding to drip out over the metal, caulking it would trap it behind the siding.

Windows should be caulked for air infiltration, and caulked on the inside. It is usually inadvisable to caulk windows on the outside, because it traps moisture around the frame and causes rot. The exception is if wind drives rain directly against the house, like the windward side next to the ocean.