L..
I have an extensive background in music (vocal performance), and while I was in college I did a lot of solo work (some for weddings). The bride always gave me the music to her song choice; sometimes I knew it, other times I didn't. They didn't usually ask for a foreign language aria, but it wouldn't have been a problem if they did. To be perfectly honest, maybe you could brush up on some country romance hits...? The majority of the weddings I've been to and sung at have had songs by Rascal Flatts, Leann Rimes, etc. Some are in the pop genre too, especially for younger people getting married.
For weddings, I'd generally stay away from a Pie Jesu....They can be very very beautiful, I've sung many myself, but they are in requiems, and often sung as solos at funerals. The lyrics ask for granting peace and everlasting rest..Not really marriage material.
Sounds like fun! Good luck!