Hi,
1. Yes, the SQL queries from that post
www.hikashop.com/forum/4-how-to/77039-de...database.html#119092
are still relevant.
Note however that it also contain queries to clear the carts and the orders on your shop.
2. I suppose that you mean "responsive" and not "responsible". The page between the checkout and the payment gateway is necessary, however, HikaShop only displays one line of text and a button to click if the redirection doesn't happen automatically. So it is already responsive and should display well on any device.
Your screenshot is a screenshot of an email notification, not a screenshot of that page, so I'm not sure we're talking about the same thing here ?