Yes 1.6L 4-cyl. Yes 1985-89 exc. Yes Porsche All 4-cyl. The USA doesn't show any signs of going metric in the forseeable future. Or 72 months.
Some engines have two belts.
Or 144 months, whichever comes first. At high engine speed. Engine service schedule ends at 50,000 miles. Depending on cam position when the engine stops, the engine may escape damage, as opposed to most others, which are always damaged. A compression check will tell if there was damage.