Hi,
The standard HTML file upload system is blocked by safari on iPhone. That's a limitation of the browser itself because apple doesn't want you to browse your files on your phone. You can however use it if you use opera instead. We tested it and it works fine with opera.
There is a message saying that there is a 2M limitation. If the upload fails because the file is too big, you will get an order message. It's not possible to have such warning with the standard HTML file upload system. That would require to use a flash based upload system which is more complex to implement and wouldn't work on iphones because flash is also blocked...
It's the exact same thing for the progression of the upload. It's not possible to display it within HikaShop with the standard HTML file upload system. However, modern browsers like Chrome display either the upload percentage or a progress bar at the bottom of the screen while the file is being uploaded.
If you want to list all the products, just go in the main product category and change the filter on the right to "all sub elements" instead of "direct sub elements".
For the thumbnails, there is no option for now, it's in the todo list.