Hi Ram,
Easiest way to find dependencies between templates and tasks is the workflow explorer transaction SWDM. It has a number of good search mechanisms.
Suggest you raise the 2nd question separately - putting 2 questions in one post tends to lead to confusion and neither question getting answered correctly.
Also I'm not sure if you really mean the workflow templates and tasks or the work items they generate. A little more info on a separate discussion please.
Rgds,
Jocelyn