@chrystel: I just check in your account and you are using Catch Everest Pro theme. I also see the home in the menu. All menu can be managed through “Appearance => Menus”.
About the update: All your edits done though Theme Options panel and Custom CSS will not be reverted back. But if you have customize any core theme files like index.php, header.php, functions.php, style.css and so on. This will be reverted back to original when you update the theme.
About the slow. I see that the images in the slider are heavy. You can reduce the size of those image from Photoshop. Edit that image to 1140px width and 450px height with optimization. Right now your image are too heavy.
You can also use “W3 Total Cache” plugin to cache your site.
To change the font you can go to “Appearance => Theme Options => Font Family Options”.
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