going into a turn

That is the biggest problem I have with my son right now. Everytime you pull in the clutch entering the corner you'll change the attitude of the bike, and this leads to inconsitency. All the schools here teach a rider to downshift let the motor do some braking and it helps keep the rear tire stuck to the track. Give the motor a couple burps to make sure it'll be in the power upon exit, if not downshift. "Sometimes" a clutch feather is needed upon exit but again this could lead to inconsitency because you'll be relying on the clutch to make up for poor gear selection.

I keep asking my son to stay off the clutch upon entry and carry enough entry speed to keep the motor in the power on exit. This is a huge struggle for us because he's been relying on that clutch to get him out of the corners harder BUT this has also lead to falls from spinning out if he isn't in a good rut trying to make a pass.

Being smooth and consistent is the key, speed will be built off that.

I only use the front brake to slow down for the corners, not in the corners. I try to go into the corners as fast as I can with out going over the berm/rut and still be in control.

Fingers on the front brake will help if your climbing the berm apply a little pressure to plant the tire harder and bring it back down.

I use the front just enough to set me up for the corner/ making the front bite but I do this upon my entrance never in the middle, I'm already back on the throttle after I've set myself up usualy before I get to the middle of the turn. If it's a tight bowl turn then you can enter hard, use the back brake to sling the back end around, but before you lose much speed pop the clutch and be on your way. Body possision is key to it all to.