Your instructor more or less has the right advice. Don't be scared of the stall warner (on this occasion!!!). Most stall warners will go off 5 to 10 knots before you actually stall. Get him to take you up to a safe level and demonstrate this to you. With 2 stages of flap, note the speed at which the 'plane stalls. Then take that speed and multiply by 1.3 and that is a very safe speed you can use for approaches. This is higher than the initial speed you will leave the ground on short field take offs. Then get him to demonstrate slow flight, right on the edge of the drag curve, with the stall warner sounding, but retaining straight and level flight. That way you will see for yourself that you will not fall out the sky.
On a short/soft field take off, the aim is to get yourself off the ground so that you can accelerate to best climb speed. This acceleration is done in ground effect as you say. As you initially drag the 'plane off the ground the stall warner will go off. As you feel the wheels leave the ground,
gently nudge the nose forward to remain in ground effect. You will be wanting to keep yourself just a couple of feet off the ground initially. Once you have gained speed, which will happen remarkably quickly, you can then climb away.
Do be careful though to only nudge the controls forward, you don't want to stuff the 'plane back onto the ground nose wheel first!! You will soon get the feel for it. If you are not fast enough and only a couple of feet off the ground, the 'plane will alwys land back on the ground. On a rough field you will find yourself taking off several times across the bumps!!!
Do keep all control movements as gentle as possible whilst the stall warner is sounding and whilst you build up your speed. Large movements of the ailerons cause the stall speed to increase.
For those UK pilots - the CAA do not allow the use of 2 stages of flap on the PA28
