About the zoom problem I had, here is the fix Jonny of https://www.sunnytoo.com/ gave me:
How to fix the Zoom feature for XF V3
Make sure to enable the zoom feature in the Theme editor module. Here:
theme editor > general > Zoom product images on hover: make sure "Yes" is enabled.
AND on Product page tab in the Theme editor module:
theme editor > Product pages tab > (search for zoom):
Select from these choices:
jqZoom or Fancybox:
Standard zoom - I selected standard.
Inner zoom
Fancybox
Code updates:
Reactivate the zoom feature. Edit the \themes\transformer\css\responsive.css file.
Replace this code:
span.viewscrollspacer,
#viewscrollright,
#viewscrollleft,
.zoomPup,
.zoomWindow {
display: none!important; }
With this:
span.viewscrollspacer,
#viewscrollright,
#viewscrollleft {
display: none!important; }
and
Remove this code from the /themes/transformer/css/global.css
Which is
body.mobiledevice .zoomPup,
body.mobiledevice .zoomWindow {
display: none!important; }
Works great! Zoom makes my site 100% better in my opinion.