Yes, so the ability to positively test a coin for metal content will be of some significance. For the average joe, there'd be no realistic way to make such a determination on raw metal, so a proof mark would be about as good as they could hope for.

Not too practical to travel 30 miles by foot to do work for half a dozen different people over the course of a week or more, and get paid in chickens, pigs, sacks of grain, or cords of wood. There are so many problems with that scenario, and besides, that's not how most of the crops, herds and flocks would be disbursed anyways. Far more practical to accumulate credit so that when the produce/livestock do come to market you can acquire as much as you need at an optimum exchange rate.

Direct exchange of goods and services can work. If you have a strong, well rounded community it can be viable for a while, but mobility and convenience should eventually dominate people's methods.