How to update the theme? Just install the new version as regular theme (without demo installation). Feel free to ask for support if it’s not clear!
Is your theme compatible with ShopEngine? The theme is based on Elementor, and it fully supports WooCommerce, so yes, the theme should support extensions like ShopEngine also.
Does the theme support custom fonts? Can I use my own font? Yes, you can choose any in Elementor Global settings to set globally or change only on a specific demo.