Hi Agatha!
1). In principle there should not be a difference with respect to where you upload the image from – e.g. the logo I’ve added to your website was uploaded from my computer. Just be sure to press “File URL” and it should work fine. If it doesn’t – let me know!
2). Regarding the second issue: it did not look like a theme problem, but I’ve decided to troubleshoot it anyway. It seems that one of the plugins you’ve installed, namely “vSlider” – it probably loads an incompatible jquery library which breaks the native uploader. I’ve disabled the plugin and now image upload works fine on all pages, posts, and portfolio items, as well as in the Theme Options panel. By the way, you can use Fuji’s built-in slider, which provides similar functionality ;)
I hope that helped, do tell me if any of the issues still persists!
Sincerely,
Andrew | Satori