Hi,
good to know about answer.
1. you can check the jobs in SM37 and in PRD they are mainting the 5 or 6 server then check the TX-SM51 open the one by one server then check it respective users.
2. some time jobs running long time (2 or 3 days) that you can kill means cancel and stop means stooping the job in SM37. there is simple difference kill and cancel job.
3.yes it is possible.
4.use the repair full request in info package giving the some data selections.
5. VBAK,VBAP is the tables not tcodes . tcodes for the sales order create VA01,VA02,VA03.
Thanks,
Phani.