slowing down and stopping......
ive had a few issues with this myself! the best way, as has been said, is to slide the back of the board to bleed some power.
but i can hear you think "how the hell do i do this when i am getting lurched on to my toes?" ok... this bit sounds back to front but i reckon its the all time best begginers advice..... keep the kite low.
although more powerful, you get a lot of horizontal pull which is easy to power slide against, instead of vertical which isnt because you feel like you will face plant.
if you keep the kite low it will eventually work its way ahead of you and over to the edge of the power window. then you can just fly the kite out of the window whilst carving up wind and stop.
if you keep the kite low you will also be able to go up wind much easier as you will hold your line much better rather than getting pulled upwards and losing friction on the ground.
finally, when those gusts hit, the kite will lurch froward when low rather than YOU lurching onto your toes when the kite is high and a gust hits.
some geezer told me this in the park when i was learning and it sorted me right out. hope it helps you too. have fun
woodsy
ps i once couldnt stop, didnt have any kite killers so let go of one of the handles which promptly shot off at a hell of rate and nearly killed someone. not good.