Does this plugin work with Simple press?

I’m not aware of any compatibility issues against Simple Press at this time. s2Member is also compatible with bbPress.

Does s2M integrate with Simple Press as far as protected sections based on ccap or levels?

Custom Capabilities integrated with Simple Press would require a little bit of custom code to work with your theme. See: https://www.s2member.com/videos/A2C07377CF60025E/

However, s2 Membership Roles can be mapped easily; as this is a feature offered by Simple Press under: Simple Press ? User Groups ? Map.

Screenshot: https://imagizer.imageshack.us/v2/800x600q90/6/3f93.png