Hi Nayon, and welcome to the forums... you have obviously posted before but this is the first time I've seen you around
To answer some
of your questions...
Yes you can to some things that will allow you to drag around physics objects. Just remember, that physics behaviour ONLY works by applying physics forces to it. You cannot assign other behaviours to physics objects as they will spaz out.
To make a simple click and darag function, you could do something like:
+Mouse button is down
+Mouse is moving
-Apply force of MouseSpeed at angle MouseX, MouseY
To find out if the mouse is moving you would need to compare coordinates. I'm not 100% sure how this would work, but I assume you would use "lerp" to calculate the difference in X and Y position of the cursorr.
Using "lerp" you should also be able to figure out the angle at which the cursor is moving, or just use the current X and Y coordinates of the mouse as the "launch" destination.
It all depends exactly HOW you want the objects to move. Are you picking them up and moving them "god style"? Are you throwing them like a half-life 2 phys-gun? Are you giving them momentum and "coaxing" them around the screen?
Answer this, and perhaps a clearer/simpler solution can be derrived.
Also, to find out if an object is moving or not (assuming you are talking about physics objects still) you should be able to compare the velocity of the object.
+PhysObject velocity equals or less than 0
+PhysObject velocity greater than 27
+PhysObject velocity less than 132
-Do different stuff
Lastly, hinges I believe cannot be broken without destroying one of the objects and recreating it in the same position using a loop. I use this in my tank battle game when repairing the treads (since it uses many small hinged physics objects). You can destry all objects in the required conditions, and recreate them instantly in the same X Y coordinates, but without re-hinging them.
If you need more specific details on this, then let me know I should be able to help you out pretty good on this bit
Hope that helps!