I was wondering if there any tool for these functions (preferable opensource else any other commercial tool)
1) I should be able to Import requirement document from MS word (As all the functional people are writing the requirement in MS Word only)
2) I should be able to define a no to each paragraph or line as per my requirement on imported requirement document
3) i should be able to write test cases based on each requirement Id and then should be able to Map each requirement ID to test case Id
4) tracking the changes in requirement and test cases
5) finally exporting the test cases in MS Excel format
I heard this is possible in Telelogic DOORS tool,
is there any other tool or opensource
You can do this and a whole lot more with DOORS from Telelogic. You may want to have a look at 'Implementing Testing with DOORS at Dräger Medical' (Presentation from the Telelogic User Group Conference October 2004 in Germany) at: http://www.grahlmann.net/presentations.htm
For sure, you could start with Excel + Access and write a whole bunch of VBA. Everytime, you wrote a piece, you will want something more, you will write more, until you spend much more money than a proper tool like DOORS would have cost you in the first place.
BTW: DOORS comes with a programming language 'DXL' which allows you to customize DOORS if there is really something you need to add.