Thank you so very much for your reply.

 

Actually, I've figured out most of my needs till now, I even found a way to achieve the hardest thing I needed (an appropriate icon next to the file uploaded).

 

It's a single replacement in uploader.js, however as it involved some RE to figure it out, I'm not quite sure if I'm allowed to post it in here to help others, or keep it for myself...

 

Anyway, the final result of my "hack" looks like this: