change jumping in the character controller

when I jump using the character controller unity3d provides I'm still able to click shift and start running while I'm still in mid air. I want to know if I can make the player go back into walking speed just before the jump so the jump will be like how it is when you just walk. last think I want to know is if there is a way to add a delay between every jump because the way the character can just jump and jump over and over again kills the game I'm currently making, I never really touched any of the code that is provided with unity itself so I thought I should ask if these things are possible and if so how I should do it (some tutorials for example)