Hello,
1 - With the current indications, I'm afraid there is nothing related to HikaShop but it looks like more an incompatibility with a configuration of your web hosting or third party plugin.
I can see for example some HTTP headers with a mention of K2
X-Content-Powered-By:K2 v2.7.1
Also, please try to avoid space in canonical URL ; that's not best for SEO, SEF, etc.
2 - As Mohamed mentioned, it would require some customization.
www.hikashop.com/support/documentation/1...-display.html#layout
Now the thread he linked you is mostly for HikaShop 2.6.x ; if you're using HikaShop 3.0 with the new checkout system, the modification would be a little bit different (but the main idea is still the same, the view would be different).
3 - We can assure you that there is a setting for the quantity input in HikaShop configuration :
www.hikashop.com/support/documentation/5...html#display_product
Regards