The General Board of Discipleship of the United Methodist Church provides help for planning worship music here: http://www.gbod.org/lead-your-church/music
And resources for hymns here: http://www.gbod.org/lead-your-church/hymn-resources
Lists of hymns by Charles Wesley, some with notes and background:
http://www.cyberhymnal.org/bio/w/e/s/wesley_c.htm
http://gbgm-umc.org/umhistory/wesley/hymns/
Sites with stories about the history of certain hymns:
http://www.lectionary.org/hymnstories.htm