[quote="TrueLight, post:10, topic:246617"]
So I was wondering.....Is this a regular mass where parishioners attend or is it just the priest offering the mass?
I thought it was offered at religious houses.
Also, in what way does it exclude? I see daily masses offered for different people all the time.
If you attend the TLM daily often requiem masses will occur (at least where I go) as a votive mass. The requiem mass basically cuts out all the parts of the TLM that would be inappropriate for a requiem. Thus, the prayers at the foot of the altar are basically cut out, the Gloria is omitted, as is the creed I believe, the Angus Dei rather than asking for "mercy" asks "grant them peace," and the ending rites are altered a little bit. In addition the Priest wears black, which is a bit shocking to see for the first time if you are used to the Novus Ordo.
I had never heard the specific tradition you mentioned, but from you posted I don't see anything incompatible with Catholic teaching. It never guarantees the release of the souls after 30 days. And yes praying for the dead, which is what the requiem mass is, is a very Catholic thing to do.