Regarding the issue of substitutes in cricket, it works slightly differently in cricket. In cricket, there are 2 umpires on the pitch. One stands on one end of a pitch. The other stands parallel to the pitch at a farily large distance away from the pitch. He is called as the leg-umpire. His main purpose is to make decisions for run-outs and for bouncers that are too high. The two umpires switch places after every over.
The one standing at the end of a pitch is the one that is most important because he is the one that takes the decisions against leg before wicket which is one of the toughest decisions to make for the umpire. Also he keeps an eye out for no-balls. A no-ball occurs when the bowler steps his foot out of the crease and bowls at the batsman. This is called as a no ball and is an illegal ball because it gives an unfair advantage to the bowler as he is too close to the batsman.
However, there are other drawbacks to bowling a no ball too. One of them is the fact that if the batsman gets out when the bowler has bowled a no-ball, he is given not out. Recent changes in rules for live cricket matches has also made it possible for a batsman to get an extra ball bowled at him in which he can’t get out either. So that is very bad for the bowler and has to practice very hard at the practice nets to make sure that he remains disciplined and does not overstep when he is bowling.
Another way of giving away cheap runs as a bowler is to bowl wide balls. A wide ball is when the ball is bowled too wide from the batsman. It is unfair to the batsman and is termed a wide by the main umpire who takes the decision in this case.