After a person has attained Acaryan’s Tiruvadi, on the day of Shubham, who amongst the Vaidika-s, non-Vaidika-s, men, and women is qualified for the Veda parayanam? During Shubham, which portion of the Vedas is recited during Veda parayanam? During the Veda sattrumurai, must we recite only those Veda panchadi-s graced by our Acaryan?

Women must not recite Vedas. Among the men, those who have learned Vedas properly can do Veda parayanam. On the day of Shubha, generally, Upanishad can be recited. If possible, a small part of Samhitai can be recited.
For Veda sattrumurai, there are prescribed Veda panchadi-s (The last panchadi) for recitation. Books are available for this and can be relied upon.