There are no limits to add pages, categories, products.
Regarding the customization of colors, every theme comes with a file called "custom.css":
in this file, with a basic knowledge of stylesheets (CSS), it is possible to change colors without modifying the theme files so as not to lose the customizations to the next theme updates.
In any case, for small changes (like those related to colors), we are available for free through this ticket system.
Last Updated: 29 Oct 2019