The best way to add another font would be to add it to the front-replacement.php file and overwrite the other fonts. You could indeed use a plugin for the sliders, but you’ll need to either insert it on the page itself, or code it into the header. I’d only advice this if you have experience with php/html/css.
The gallery also uses posts from categories. Make sure those posts have a title and a featured image. Once they do they’ll show up on your gallery page 🙂