A year ago (it was 1st Sunday of Advent, last year, actually) I attended my first Latin Mass. I had no idea what was going on, I was completely lost the whole time… and yet, I was so enamored with it that I asked the chaplain of the Latin Mass Community if he could teach me a bit more outside of Mass. He didn’t, but my inquiry was enough for him to ask one of the longest members of the Latin Mass community to start another class, where several others including me met. I am a very quick learner, so after a few months, I knew enough about the Mass that I joined the schola.
Every week, where I attend, is a Sang High Mass, though occasionally, it is a Solemn High Mass (the difference, from my understanding, is whether or not it is priests who are acting in the deacon and sub-deacon roles, or altar servers). And as far a singing the Gloria and Credo (and Sanctus and Agnus Dei)… the congregation is encouraged to join with the Ordinaries. This past Sunday, because of it being Advent (it’s the same in Lent), the Gloria was not sang, but everything else (Kyrie, Credo, Sanctus, and Agnus Dei) should have been. Also, at my community, we do sing the Pater Noster along with the priest, though I have seen it where it is just the priest who sings it, and the congregation only sings the “Sed libera nos a malo” (deliver us from evil). I think it is only an allowable option, and not a requirement.
Please, try the Latin Mass again… the next time, don’t try to follow along with the missal. but, if you do, follow what the priest is doing (ie, are his hands together or apart, is he bowing or standing straight, is he genunflecting… etc), and follow the red parts in the missal. That is usually how I am able to keep up. Also, every once in awhile, I know that my priest will have some verbal cues (he may say the first few words for a prayer in an elevated voice, but then go back to the soft voice).
If you have any more questions, feel free to come back and ask away.