Is there an admission fee?

Yes but I don't remember how much. Worth it as it is a very moving site, especially if you are interested in history.

Nation park pass can save you $$$ if going to several parks a season.

Yes, per car load

Yes, fee, but not much and as others have said, worth the price. I have stopped there several times, one of the best historical sites you can visit. This page in history should not be forgotten, what this country did to indigenous people was a crime.

$10 entrance fee for adults. $20 per car but also covered under National Parks Pass which is $80 covers 4 people in a car and valid for a year. Under 16 yr free. Free entry during National Parks week. No booking necessary

There is during the day, it's not terribly expensive. Just goes to the upkeep of the very historic site and well worth it.

Yes. I think it was 10-15

Yes, it's about 10 dollars.

Yes.

There is admission to all National Parks unless you have a senior pass.