I have the same problems with the selection tool. The marquee tool is much better for selections, because it doesn't move the selected parts. With the marquee tool, you can not only drag, but also click a vertex, edge, or polygon, to select the part. Shift-click adds to the selection, shift-click a selected part removes the selection. Clicking overlaying parts selects the frontmost part. Unfortunately, the reference guide doesn't mention this functionality of the marquee tool. To select and move, I usually choose the marquee tool, drag and/or click to select, and then press the "T" key to activate the selection tool and move the selection (or press "R" or "S" to rotate or scale the selection). If you have "Toolbar hotkeys are sticky" disabled (unchecked), the "T" key activates the selection tool temporarily. When you release the key, Carrara goes back to the marquee tool.