That seems to work except for 2 things. One minor problem is that if you use Transform and then want to move the layer while in Landscape mode, the arrows still operate as if in portrait orientation. Obviously that is a minor issue. A bigger (or at least more tedious problem) is that moving a layer (or rotating or scaling) requires that you repeatedly hit the arrow keys (or scale buttons) in order to adjust one pixel at a time. Holding it down does not auto-repeat. It would be great if you could just use your finger to position the layer or two finger to scale and rotate as well as have the option of entering a pixel amount or angle and have it make the transform.
But you CAN do what you want. If you select rotation, just use two fingers to rotate the layer. If you select scale, drag with two fingers to quickly enlarge. To move, drag in the same direction with two fingers. Just keep an eye on the layer you've selected, otherwise you might be manipulating nothing in particular.
To just drag a piece of a picture somewhere, use the selection tool to drag a border around the area you want, hold finger down on the Layer icon at the bottom, click Transform, then Move. Use two fingers to drag the selection to where you want to go. Click Apply. Note that this leaves you in the same layer.
On the other hand, if you want to copy a selection, rather than move it, highlight the area you want with the selection tool, hold down the Select icon, and click Copy, then Paste. The selection will now be on a new layer. To move it around, hold down layer icon, Transform, Move, then you can drag the shape where you want using two fingers, and hit Apply when finished. You might then choose to merge the two layers down to one.
It helps a lot if you're familiar with photoshop, but some of the gestures etc seem a bit odd until you get used to them. I find it really great for manipulating graphics files of music, and other things.