First to answer the question of what the SLOW capsule does. It really only applies after you've gone through the game at least once and every hit lowers the bricks. When you get a SLOW capsule it will stop the bricks from lowering.
Now for my dilemma. Playing on 4.0 I have a current score of 412,640 and 84 lives. I had the ball disappear by hitting a top brick just wrong after they lowered one level. I'm stuck with a Laser and one brick left thats being blocked by a cement brick. Is there any way of possibly killing myself without restarting the game. If not I guess I may be restarting. How depressing if this is the case.
Here is a pic if it helps. Sorry I didn't flip it but you get the idea.