What is the average height and weight for a 3 and half year old boy and what present should he be in?

It depends. Depends what his height and weight were when he was born. The average is different for different kids. The important issue is the rate of growth, if that is normal. Kids this age gain an average of 3 to 5 pounds per year and grow about 2.5 to 3.5 inches per year.