Measurements in different systems

Yes, well- the recipe was offered up freely, after all. Perhaps the recipe author simply recorded the amounts listed on the packages of things he/she used to create the dish. Measures of things like salt, pepper and olive oil are not so critical that erring a bit should have much impact on the final product, either. As Gammy said, perhaps it's worth the time to bookmark a conversion site. It might make things easier for you.

In a perfect world, yes. My advice is to bookmark a good conversion website such as : https://www.thecalculatorsite.com/cooking/cooking-calculator.php or this one for baking from King Arthur flour: https://www.kingarthurflour.com/learn/ingredient-weight-chart. With smaller measurements, such as fractions of teaspoons, it is actually more accurate to use the tsp. device rather than weigh out.