MichelB wrote: ... I wonder if you can rotate freely as in PSE. You also have the 'flip' horizontal or vertical option in PSE, but no arbitrary rotating?
In the same way, I often wondered why I did not find a 'crop' option for layers only.
To do this, I use the rectangular (or ellipsoidal) marquee tool, inverse selection and delete. A 'crop' option for layers would be handy, maybe I have missed it?
There are two ways to rotate freely in CS4; Both involve choosing Edit > Transform > Rotate. From there you can either position the curser outside the image where you get a double headed curved arrow. The other way is to use the scrubby slider at the third option box from the right or by typing an angle into that box if you know exactly how much you want to rotate. By default the layer rotates around the center of the layer, which is shown by the little circle with the cross hairs. If you want to change the axis of rotation, simply move this center to another point, then rotate the layer.
As far as a crop tool for layers, All layers must be the same size; you can not crop one layer to be a different size than the others. You can erase pixels in the layer by making a selection and using the delete key as you are doing, or you can select Edit > Clear, which also deletes all pixels in the selection.