It depends on the length of the manuscript. If it’s an e-book you can publish it for free.
It depends on the contract you have with the publisher or if you are self published and the price of the book.
It depends on how many pages it is and what printing service you are using or if you are using a traditional publisher.
It depends on what publishing option you are using. If you have a deal with a traditional publisher you do not have to pay.
Yes
Usually not that much but it depends on how well it sells and how well it was marketed.
There’s no right answer. Depends on the work.
Depends on the author and if they feel like it’s really something they need to say and think can sell.
For print books, maybe about 3-5K books, but the metrics vary depending on the platform and the media outlet that considers
You can compare it to other similar books in similar genres and length and price accordingly. Hardbacks usually go for around $20 US dollars while paperbacks are more around $13 or $14 for adult fiction/non-fiction. Depends on the length and the genre.