Two keys to control movement and rotation along three axes – it sort of works and probably should be kept, but I second the suggestion of <modifier> plus four [was six] movement keys for these things.
Or use two keys to switch orientation (rotate, change axis) and the usual movement keys to slide the block around on the attachment location being pointed at, perhaps. A representation of which axis is current and how the movement keys affect it would be needed too – a combination of a labelled cross for {-X, +X, -Y, +Y} and three axes, one highlighted, indicating which is current for rotating.
Outline it in white to indicate a valid attachment, shade it in red and superimpose a cross to indicate an invalid attachment.
Regarding right click – it's perhaps too simple. You just click and some action is performed; control over what action is needed. That would complicate the controls but make actual usage easier.
