Well go to www.midifarm.com.
The midi-files with lyrics are called KARAOKE. Search for Karaoke files *.KAR and you will find the same midi-files WITH lyrics ! Hope this helps.
As to the second question: I would also want to know how you put in lyrics !! But I think it is rather complicated since there is a line walking along the text showing you what to sing. Anybody can help?

Ilija