forehand loop

where is correct contact point of ball for forehand loop shot?

Right on the sweetspot.

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Depends what rubber your using.... Ive never played with tackiness so i wouldnt know. :s

I find with euro rubbers, u hit the back of the ball and brush upwards

Its a give and take on ease and penetration. A normal loop is the easiest and spinniest but happens to be less effective for the modern game than the Chinese loopdrive. You'll notice that often these loopdrives have both the properties of a loop and a smash, making them a potent weapon. In a loopdrive compensating for spin is done with the motion (more upwards for backspin) and not the blade angle, contact should be flat and upon penetration into the sponge the wrist pronated so that the sponge doesn't bottom out on hard shots.

I was taught to two loop drives:

Lifting drive:
against low heavy chop use vertical racket
near vertical stroke concentrate on spin not forward power. Ball has high arc and kicks high
Sinking Drive:
against high ball too deep to kill, loop drive forward over top of ball generating max forward power with spin. Ball has low arc and dives to floor.

The sinking drive stroke is more or less the same for loop driving against block

Of course the actual contact point varies with every shot but if you keep these models in mind you will develop the right instinct for the shot.
Remember:_
1 a ball lower than the net MUST be lifted.
2 If you lift a high ball it WILL go OUT!