I scanned some books when I didn't have wifi access so the titles did not automatically come up. Is there a way to have the app search again to identify the titles of the isbns?
Yes. Go to Settings -> Update Entries then select search by ISBN. You can select the filter by missing title to only search for the ones that were scanned without completing the searches.
How do I download books?
Book Crawler is not an ebook reader, but instead is intended to catalog your books in a central location. It is possible to download books available via Google Books and iBooks. To do this via Google Books (from the home screen), press Books -> New -> Google Books. You can use the filter to select the type of book you are interested in (e.g. free or paid eBook). After entering the isbn, title, and/or author you are interested in, press a book you would like. Now press the "i" button -> "Edition Information". You should see a row that says Google Preview and a row that has a link to downloading the book via Google Books. Pressing the last button will redirect you to Safari to continue your purchase through your Google account. If it is a free book, the last row will contain a link to the pdf and/or epub version. Selecting one of those will redirect you to Safari where you can continue download of that book. To download a book via iBooks, press the search button then Apple Store. After selecting a book, you will be redirected to iBooks.
How do I delete a genre?
There is a switch under the settings page called "Predefined Genres" that when set to OFF will remove the pre-populated genres from being displayed as a selection (unless that genre is defined in a book).
Genres are simply pulled from the genre attribute on a book. If you delete every instance of that genre, then it will no longer appear. You can create a smart collection for the genre you want to rid of where the rule is something like 'book genre contains "foo"' to see where that genre is being defined. Then when viewing a book in this collection, you just press edit, then genre to set it to something else.
How can I maintain a wishlist with Book Crawler?
There is a "wishlist" tag that you can apply to your books. Select a book that you would like to appear in a wishlist and press "Edit". Scroll toward to the bottom of the page then press "Add Tag". Select the "wishlist" tag and save the book. From the main screen, select "Tags" then "wishlist" to see your books.