If they're cared for properly, absolutely. Wash them [by hand] in warm soapy water after using them and toss them in a drying rack to dry. Good as new. Avoid letting them soak in water or with dirty dishes for days. Don't put them in a dishwasher. When they start to dry out, you can reapply some finish. I sell some spoon finish in my shop, or a cutting board oil would work great.
Short Answer 1: It depends on the scoop. Short Answer 2: It doesn't matter. Consistency matters a lot for a good cup of coffee, but you can adjust number of scoops used per whatever scoop you like to use. So the actual size of the scoop matters less than using a consistent number of scoops once you figure out your sweet spot. How big are the coffee scoops that I make? It varies. I don't use templates and my process isn't automated. Each scoop is made by hand and eye. It tends to average out to around 2 tablespoons, but it can vary from scoop to scoop.