When using Free Transform, the "Reference Point Location"(or center point) can be changed to determine the location around which transformations occur. You can drag the center point freely within the image area, or set it numerically using the Options bar. This can be particularly useful when trying to align objects or rotate around a point that is off-center.
To toggle from Free Transform to Warp mode, click the warp icon in the Options bar. While in Warp mode, Command (Mac) / Control (Win) + T toggles to Free Transform mode.
When in Free Transform, images that contain information beyond the visible image area may not display the transformation handles at your current zoom level. Instead of zooming out several times, select Command (Mac) / Control (Win) + 0 (zero) to zoom out - to “fit” the transformation handles on screen (just as Command (Mac) / Control (Win) + 0 (zero) will “fit” the image on screen when not in Free Transform).
Command (Mac) / Control (Win) + Shift + T transforms the layer(s) again by applying the same transformation settings. Option-Command (Mac) / Alt-Control (Win) + Shift + T will create a copy on it’s own layer while creating a duplicate transformation.
Command (Mac) / Control (Win) + T brings up the free transform bounding box. Holding the Shift key while dragging any of the corner anchor points (handles), forces proportional transformations while Option (Mac) / Alt (Win) transforms from the center. In addition:
• Command (Mac) / Control (Win) freely distorts an image.
• Command (Mac) / Control (Win) + Shift skews an image.
• Option-Command (Mac) / Alt-Control (Win) + Shift changes the perspective of an image.
To apply a transformation tap the return or enter key, to cancel a transformation hit the escape key.
When selecting multiple objects with the Move tool, you have the option to check “Show Transform Controls” (in the Options bar) to have Photoshop display a bounding box around selected objects (content on layers). Not only does this help to show which layers are selected but can also be used to quickly transform an object without having to select the Free Transform command.