p-pat-ni

You could use Goodreads to keep track of books 'to read' and 'read'. Adding a review once the book is read, will help you summarize it and retrieve it later.

None I believe (unless its an affiliate links). But the focus is on the person reading that tweet.

That's interesting. I generally add whatever I would like to buy later to my cart instead of wishlist. I never visit the wishlist and by adding to cart, it reminds everytime I checkout something else.