we're about to spend 10 days road-tripping in the fjords area in the first half of June. some of the routes between locations require taking a ferry. how does that work? can someone perhaps give some details from their personal experience? how frequent are the ferries, how do we pay for them etc.

most you just roll up, form a line or queue, roll on and pay the guy on the deck. Sometimes you pay on the shore before you roll on. Very chill, you chat, you watch the water, you eat an icecream, you drive off the other end.

Assume you have a rental car. It will have a (transponder) that will pay your toll automatically. You just get in line, drive on board and drive off. Could not be any more simpler

Frequency depends on the ferry. My recollection is that you can find times online

There are a number of you tube videos describing all.

Here is a good one.

I meant to note that there are some routes that are considered a "tourist" ferry and not a normal "road" ferry. For example between Hellesylt and Geiranger. For at least some of those and in high season I have seen it recommended to book in advance if you have a car. More google searches can help you distinguish which is which.