Posture

when u see the pro's stand over the ball, there's a straight line from there lower back all the way to there head, but for me my head dips down in my stance. Wondering if this effects anything, should i change it or should i keep my head up.

Instead of looking only at the head angle, look at the whole spine angle. Compare yours to theirs.

Perhaps their spine angle is steeper than yours so their head angle looks shallower than yours by comparison.

It's the difference between bending at the waist and bending at the hips.


ML

you should be looking at the ball down your nose, otherwise your chin gets in the way of a full turn.

This is something ive worked hard on the last few months and it makes a BIG difference to your swing plane. At address try and feel like you almost push your shoulder blades back and out and lift your head up off your chest. This will make you feel like you are taller at address so you flex your knees a little more to get down to the ball. You can feel 'the sitting on a bar stool' analogy here too. and will sense you are looking down your nose at the ball

This faciliates a much better turn and coil. Slumped shoulders will cause all sorts of problems

Reason for tilting your head down : so you can see the ball.
Reason for tilting your head up : so your left shoulder can go under you chin.

There's really no need to tilt your head any further down that the point where you can see the ball from address. I would say, tilt it as high up as you can, as long as you can see the ball. For me, it really loosens up the posture/stance and the strain on the shoulders. If you are bent correctly at the hips and knees, with the clubhead on the ground and hands hanging relaxed, that posture is good enough.