Hi Sairam,
First of all, I asuume that you are creating the Appraisal Templates by PHAP_CATALOG_PA. Is that right?
Now, regarding your questions, you are asking lots of questions and they all are general. So I can try guiding you for some of them:
1. As Samuli have written, there are several web solutions for handling appraisal processes, such as BSP (Business Server Pages) or the new GUI with Web Dynpro for ABAP, which is also available for EHP4.
2. The appraisal templates are very flexible and that's why configuring them is considered to be quite a complex task. If you specify what you need, I can tell you if it can be configured in the template.
5. You can calculate what you need in the template level --> Columns tab --> choose the relevant Value Determination. In addition, you may use the BAdI HRHAP00_VAL_DET.
6 + 7. In order to map the appraisers for the employees, you may use PHAP_PREPARE_PA and select the proper wizard tool. The wizard also enables you to choose the proper template for each employee/employee group.
Regards,
Liran