Hi,
We can have a look at your website to see if everything is working properly regarding the images. Could you provide a ftp account, a back end access and a link to the page where you have the problem via our contact form ?
www.hikashop.com/en/contact-us.html
Regarding the sorting on prices, it's an extensive processing, so if you have lots of products it's normal that it takes lots of resources. That's because the prices need to be calculated dynamically based on currency rates, fees, discounts, variants, etc. So the SQL query becomes really heavy. The only solution would be to precalculate the prices automatically with a cron so that the results could be used directly for sorting, without having to recalculate everything. That's possible, but not something I can fix for you in a few hours, paid or not. That would require proper development and is not a small task.