Are the current Eastern-Rite Masses similar to the Pre-Tridentine Masses?
First off, the Eastern Churches do not generally use the term “Mass,” but rather Divine Liturgy or Qorbono (various spellings).
The eastern churches are NOT the last refuge of Traditional Western piety, but are in every sense of the word (including canonical) sui juris.
The Eastern Churches and their liturgies are older than anything in the West, even before Vatican II or Trent.
If you look for one-to-one correspondence with Western practice at very step of the way, you’ll get horribly confused, possibly disappointed, and probably vexed.
If you accept the Eastern Christian liturgies on their own terms, you will find them an amazing treasure trove of spirituality.
(This reminds me of a story of a teacher who went on a trip to Russia and came back gurgling about it to a colleague. “Did you know their services aren’t like ours?” she asked him, not knowing that he was in fact Russian Orthodox.)