1) Is Brompton-Gore, QC near Valcourt, Shefford, QC? Yes, actually both were in the old county name of Shefford. The birth record may have been wrong depending upon who gave the information at death. If I was not doing genealogy, I wouldn't even know where my mother was born, but I could guess. :^)
2) Where to find information on Joseph R. Meilleur? Where do you live? Perhaps there is a French-Canadian Library nearby that you can visit for more information. There are libraries in QC; Manchester, NH; Tolland, CT; Woonsocket, RI; and one I think in Michigan and NY State. Other genealogy librarires in Boston and Arlington, VA may be able to help too.
Now that you have the marriage date and place, you could also request a copy of the marriage certificate from the local town hall or church, for a fee of course. Find their phone number, call them up, find out how much, and send all information you have to help them. Don't forget to send a self-addressed envelope too. This would have the names of his parents and maybe where he came from.
Again, check our data because we may have errors. Most of our souces are second-hand, not primary documents. Better to have the primary sources.
www.geocities.com/Heartland/Farm/5233/ Canadian Fontaine Genealogy Association