Is it necessary to visit both?
I was planning to just go with a friend and pray the Rosary at a cemetery. Also, is there a special prayer for offering the Rosary in suffrage for the poor souls? Or should we offer the Rosary with that general intention?
Ave María
It's been my understanding you visit both. On another thread someone mentioned when they were young they'd ride their bikes from one to the other several times. In the '50's we were fortunate the cemetery was right next to the church so we made several trips that day.
The traditional custom was to visit the cemetery, sprinkle holy water on the graves of loved ones or others, pray the eternal rest prayer, the De Profundis or any prayer, then go to the church and pray five Paters, Aves and Glorias for the intentions of the Holy Father.
The Holy Water is optional. That is the procedure that is indulgenced.
No special prayer for offering the Rosary. You could offer it for someone you knew or give it to Our Lady to apply to whomever she pleases.