To edit items in a scene, you need to select it by clicking on it on the left hand side. Once your scene is selected, all items in that scene are listed on the right hand side.
Yes. You can continue working on your existing projects even if you have reached your limit of new projects.
To edit your existing projects you only need to click the edit link under your project. You can find your most recent projects in the Recent Projects tab on your Home Screen. If you want to edit one of your older projects, you can find it from...