I am planning on starting an online bookstore, which will have around 15 million books. I'm not expecting a significant number of page views per month, so traffic will be fairly low. There's only a single product type (book), with a few informational fields such as Author, Publisher and a single cover image. There are no product variations. Payment is cash on delivery or bank cheque for now, with support for credit card payments to be added later. I need some advice regarding how to implement this.
I've enjoyed learning Wordpress and have built a few basic sites using premium themes. But I'd also like to learn Drupal so that I can build a couple of comparison websites (i.e. data driven & a little bit more complicated).
I'm under no time constraint so would I be better off waiting until Drupal 8 appears?
In Wordpress it's easy to update to the latest version but I'm not sure if it's the same with Drupal? I don't want to experience the famous 'Drupal learning curve' only to find out I have to relearn everything when Drupal 8 comes out.