Report Offensive Message

1.) There's only one drawing layer. However, you can send objects to the front or back of the document layer.

2.) You can group and ungroup using the marquee -- have you tried that? Or, Ctrl+click lets you quickly create a group of shapes. To remove an individual shape from the group, select the group. Then, click the shape. At this point, you can work on just the clicked shape, without making changes to any of the other shapes in the group.