Also, do/will these companies drop prices if/when tariffs are reversed?
This is no different from any other cost. Their cost of goods is lower in retrospect than they thought it was, so it will show up as a gain on their income statement.
What's the economic effect, though? One way to model a tariff that's later refunded is that it's sort of like if a cartel colluded to temporarily keep prices higher. Competition between firms often keeps prices close to costs, but this wouldn't be true for a monopoly or a cartel.
Whether some downstream consumer of those imported goods paid a price that would have been lower if not for the tariff is a commercial question between them and whoever they paid. Maybe they would have, maybe they wouldn't have. There isn't any objective way to calculate what the price of suchandsuch Nintendo product would have been in the counterfactual.
Every shipment from overseas would essentially have a line item for tariffs due. Just add them up.
1. Trump could decide what to apply the negative tariff to (e.g. Trump merchandise or his buddies)
2. If there's a fixed amount of money to dole out and suppliers know it, approximately zero dollars will be given back to consumers because it will be easy to capture the money on the importer side.