If you need to move the entire item, you can either zoom in and move the item manually or use the JS time adjuster plugin. You can also hold 'alt' while dragging inside of the item to move the data without actually moving the item itself.
If you need to cut and stretch, click where you want to split the item and hit 's' on the keyboard (or right-click -> split) then hold 'alt' and drag either end of the item to time stretch it.
You can adjust global time stretch settings by hitting 'alt+enter' or per-item by selecting the item and hitting 'F2.'
Is this the kind of editing you meant?