If you are not seeing the green plus icon, it is because you did not select the "use as content management template" checkbox in Site Sculptor. You will need to recreate your site in Site Sculptor, but this type click the Site Type 'Define' button and select the page you wish to use as a template and choose this option.
No. The content management feature in Site Sculptor is a limited version of what you get with PowerCMS 2. Site Sculptor's CMS is client-focused, and does not have multiple users, or a SuperAdmin/Admin concept. Also not included in the Site Sculptor content management feature is the ability to add or delete any content locations, as well as view the Developer Notes.
However, because Site Sculptor created the site, it is able to provide some more user friendly features that many clients will appreciate. For example, a link to 'View Page' is available for every page in the content management and this will open that page of your site. Also, a 'Page Optimization' feature is available for all pages and allows you to specify a Page Title and meta-data to improve SEO.