Two questions

Hello Bruin, nice site you got there!

I’ll try to help you out with a starting place. I will need to warn you that you shouldn’t do these methods on the parent theme itself, (but on a child theme).
Only thing is, I have very little to not skill with coding either, so someone else is bound to correct me 😛

I’m not sure how to change the color, but I’m making a guess that in the theme’s style.css (which you can access from the editor in your WP Admin dashboard), the place you need to change the color of the button/text has to do with the “previous” settings:

.page-links-next-prev .previous-page-nav {
	float: left;
}

.site-content .nav-previous,
.site-navigation .previous-image {
	float: left;
}

.page-links-next-prev .previous-page-nav {
	float: left;
}

As for what you’re supposed to add, I don’t know.

For footer, you can access the footer.php file from the Editor too, and add your line there…somewhere. I assume you want to get rid of the original footer, but I’m not sure what’s the best way to go about that.