During pradosha kalam, which is the three periods that are one and a half hours before and after sunset, one must maintain silence. Our elders and Acharya-s have practiced mouna vratam. One must not partake any food during this period. If possible, follow these. Learnings, kalakshepam, chanting of Sri Vishnu Sahasranam, Vedas, etc. must not done.
For Gyanam, Vigyaanam, and Pragyanam, each text like the Shrimad Bhagavad Gita, the Vedas, etc. has provided different meanings based on the context. Clarify which context your query is related to.
Svami Desikan has composed shlokas in several instances within stotrams such as Devanayaka Panchashat, Bhagavad Dhyana Sopanam, etc. If he has not composed something like Paduka Sahasram, it is because Tiruvadi has not made him do so. The respective Perumal-s were responsible for Desikan to compose the respective Stotram-s on those Perumal-s.