Ok I understand now, so a few things to discuss:
1. Yes all Evaluators should be using the same form, a form is something that is applied to a domino document to say what fields it has and structure it follows etc. So yes in the case of a performance review where everyone is giving there opinion (whether text or radio buttons saying select 1-5 based on performance) , its only really useful if you can compare all the results and add them together, so yes all the same would be useful.
2. I would probably design this system in a way where when a person needs to be reviewed, a domino doc is created with that person's details (or all these are entered previously and a person is selected, depending on your use case etc.), all the evaluators then reply to this document with there performance scores. so you would then have a thread something like this:
Name: Simon McLoughlin
Profession: XPages Developer
....
....
Performance Evaluations:
1. Jamsheed K:
Skill Score out of 5
Communication 4
Techincal 4
.....
Overall comment:
I think Simon has preformed well this year because ...
___________________________________________________________________________________________________
2. Joe Blogs:
Skill Score out of 5
Communication 4
Techincal 4
.....
Overall comment:
I think Simon has preformed well this year because ...
Then when all reviewers have completed (or on going after each eval has been added) a total could be added to the top under the person details or emailed to the person / manger to let them read their score.
This type of system would not need any consideration to being parallel or have to deal with threads. I would HIGHLY recommend looking at the discussion template application. Either the new one that comes with the ExtLib or the old one thats preinstalled with your designer or domino install. The discussion is a very generic thread based forum site, the idea of how to create a thread / reply would be quite similar to the above and give you a good working example to explore while trying to design yours. A few features of the Teamroom such as emailing and the whole review process might be helpful to look at also.
Hope this helped.
Simon