Near first appears in episode 26, appearing in most episodes after that.
Episode 11.
Mello comes into Death Note in Chapter 60, in Volume 7, after L's death. He and Near are the two possible successors to L, but Mello refuses to work with Near and decides to go after Kira on his own, kidnapping Sayu, Light's younger sister.
In the anime, he appears in every episode.
It's Taiji from Death Note OST III
Near was first seen on the last scene on Episode 26 of Deathnote who was inform that L was dead. This was also the first time that Mello was seen in the anime.
Near from death note because he actually won the battle in the end
There are 37 Death Note episodes in English.
Assuming that you are referring to the large overly maniacal laugh that Light does when he is revealed to be Kira by Near, that is episode 37. Otherwise he laughs a little in almost every episode.
episode "19" 5 minutes in
Episode 29, 'Father'.
Chapter 83, according to Death Note wiki.
Episode 28