I don’t believe Calibri is a web font, so if you use it, it won’t be consistent. This means if a user doesn’t have the font installed on their computer, the font on your website will look completely different for them.
Instead, I suggest finding a Google Font that is close to the same look – this way the look of your website will be consistent to everyone.
You can try adding your image to the header widget in “Appearance > Widgets”.
What plugin are you using for your social media icons?