Touch controlled ice puck

Hi there. I've currently got a problem with my game. I got a sphere in 2D, and can currently drag it around in the frameborder I've made. But when I relase my finger, I want the sphere to continue in the same angle and with the same speed it had, at the point of relase. Kinda like the same theory, as an ice puck. Eventually I want it to stop in a realistic distance, depending on what physic material I throw on it.

My theory is to use rigidbody.velocity, but I need the angle and magnitude on the point of relase.

Here is a screenshot of the game with dummy graphic: Game.jpg

I'm using FingerGestures for my drag control.

Furthermore I got a problem with the "puck" going through the walls, if I give it enough speed. How do I fix this?

If you got any idea how to do this, or know a test project that uses this, I would be truly grateful!