Music
Is there music at a house church meeting
In general, yes, there is music. Some churches will have musicians while others will not.  Also, there is not usually a predetermined set of songs to sing.  Often, songs are suggested on the spot and as the Spirit leads.
Is there sound amplification at a house church meeting?
There is no need for sound amplification since the group size is generally so small.
Is there a worship leader at a house church meeting?
There may be someone who leads songs or plays an instrument but it would not be the same as someone on a stage.  There is no need to practice songs before the meeting so that the songs are perfect.  God listens to the heart.  While singing well can be a good goal, it is not the main goal.  
What kind of songs do you sing at a house church meeting
This will vary from house to house.  Some groups will sing more hymns.  Some will sing more contemporary songs.  Some will have a blending of the two.
Is there special music at a house church meeting?
Generally, special music is designed for a stage and an audience.  House churches have no stages and no audiences.  We all participate and interact with each other.