Hi,
The page you linked to and other product pages are inaccessible for guests and require a login. So, no exact advice will ever be possible. But this much can be said, anyway:
1. You can edit the layout via the HikaShop backend -> Display -> Views, and as described in this part of the documentation:
www.hikashop.com/support/support/documen...-display.html#layout
2. These text strings, just like pretty much every other predefined text, can be changed either in typical Joomla procedure (creating overrides in the Language Manager), but HikaShop offers you also its own tool in its backend: -> System -> Configuration -> Languages -> Edit.
Again, see the documentation for more:
hikashop.com/download/languages.html#modify
Note: if you follow the procedures as described in the documentation, your modifications will be saved and stored safely, meaning no core files will be changed, and your changes will still be there when updating.