End to end implementation of SAP e-recruitment

) How the landscape will look like?
Depends on the version you are going to implement. Also on technology you are going to use BSP / WebDynpro. Also you have to know whether you want on same instance with SAP HR or separate instance.

2) How many servers are needed? Do we need TREX server, content server etc? I need

3) How the external users will access the Portal? How we are going to provide access to the users?
External users do not need portal to access the system. They will access through the internet using any browser of their choice. They will have to register themselves through the internet to get access to some of the services. There are some services however which they will access without registering like searching for jobs.

4) How the user ID and password will be generated for external users?
You will enter your own password and user id when you register. The system will generate a password for you, only if you forget the current password.

5) Where the Resumes of the applicants will be stored? Whether it will be stored in ECC or Portal or any other external server?
while registering, the information is saved in different infotypes as well as tables. The candidate details are stored as business partner, work experience in infotype 5103, education in 5104 for example. Any free text you enter will however not be stored in the infotype but in the KW.

https://forums.sme.sap.com/message.jspa?messageID=7139065

Thanks to contributors