WordPress would be outstanding for adding a bunch of articles, that is the specialty of this blog/CMS. WP with the Visual Editor (TinyMCE) turned on, would let you change font colors and size.
WP is somewhat simple, in a way. But WP can be very complex. If you are the administrator you can use techniques and plugins to simplify the interface even more for your authors, editors, subscribers, users and readers. I recommend these to help simplify it,
http://wordpress.org/extend/plugins/ozh-admin-drop-down-menu/
http://wordpress.org/extend/plugins/wp-cms-post-control/
WP has a register / login ability built in. You can add some nice plugins to enhance it, like
http://wordpress.org/extend/plugins/register-plus/
With some little tweaks and settings, you can restrict access to the blog or certain posts/pages, so that only Registered users can see it.
However, note that WP does not have any built in abilities for charging money or fees for registration. That could add a lot of complexity to your site, theme design, and code. You can probably do it with plugins. I don't know which plugins for that. It's do-able, but it would probably not be just simple. You will need to learn some stuff and set it up.