In melodrama, what are some conventions/characteristics of melodrama and stock characters: hero, villain, heroine, etc?

Melodramas are
built upon stock characters that have entrance music which suggests their personalities.  In
addition, the music gives these stock characters the timing they use, almost as though the drama
is choreographed. These stock characters dwell in a very simple universe in which good and evil
are easily identifiable with the hero and the villain always in conflict with one
another. 

The hero

Although
the hero is always noble and good, he is sometimes duped by the villain's nefarious plans, plans
that often include endangering the heroine in order to lure the hero into a trap. But with luck
and fortitude, the hero escapes his trap in order to triumph over the villain. In more modern
melodramas, the hero can be a frontier roughneck, a highwayman, or a fireman. 

The heroine

The heroine is a paragon of
virtue:  truthful, faithful, respectful of her parents; her beauty reflects her purity and
innocent heart and complete lack of pettiness. Just at the point in which all hope seems lost,
the hero rushes in and saves her.

The heroine's
father 

The heroine's father is often used by the villain
because he can be swayed by the villain, or he may have something in his past that the villain
threatens to expose, thereby using him to gain control of the heroine.

The comic servant

As a plot device to
speed up the conclusion, according to Michael Booth in English , 

Typically this comic servant or companion instantly saw through the
villain, put the situation in perspective, and made light of the high standards of conduct by
which other characters feel inconveniently bound

The villain

The villain typically
sneers and behind the backs of his victims, he laughs a sinister laugh.  Although he is eloquent
and well-dressed, the villain lacks integrity and is not above engaging in
sadistic acts such as tying the heroine onto railroad tracks and attempting to throw her over a
cliff. 

The plot

In
melodramas in order to create excitement around the simple plot, there are often explosions,
fires, drownings, even earthquakes, and at least one stage effect.