1. CA-TDM MainFrame is built on COBOL. Now there maybe sections that are written in PL1, but most of it is written in COBOL.
2. It is suggested that the jobs are submitted on the Mainframe. Get the JCL statement output from the Subset, FTP to the Mainframe, put in/modify the JCL cards to match your ID using the Mainframe Editor for proper execution in your Mainframe environment, and submit the job from the Mainframe.
3. They can be, but it is easier from the Mainframe.
4. Yes, they are FTP'ed and then edited. If it is done on the Windows side, you need a specific editor since spacing matters. One such editor is found here: http://www.spflite.com/ but I would recommend the Mainframe option.
5. The user ID(s) that you provide should have access and execution rights on the JES2/JES3 subsystem. The job needs to be able to create and write logs for example.
6. As far as does every CA TDM User need a Mainframe User ID, I would say no. This is a matter of individual company policies. I have other Mainframe using companies that have only one user (security reasons) and a hand full (3) of people know those credentials. It also has helped in education of those individuals. As a result, these few individuals get to use the Mainframe on a daily basis - thus cementing their knowledge through repetition. This reduces the amount of Mainframe help required to do their daily work.