Dear Subra,
1. TRM doesn't have to know ABAP. He has to know how to write Technical Tasks for ABAP consultant. But if you know ABAP it will increase your possibility to understand programs, some codes. You will be able to code user exits on your own without ABAP consultant. Write small usefull and hande tools to fulfill your tasks. You'll be able udnerstand from where error and warnings come, etc.
2. 3. 4. It is better to follow the idea: "One question - one forum thread". Otherwise there will be confusion.