if that is still relevant; regarding to your questions:
- the OpenSSL is not required on the system as a prerequisite. EAP just needs to utilize OpenSSL libraries which you can get either from zip archive or rpm installation as is described in that KB article or in documentation Configuration Guide - Red Hat Customer Portal.
- this is strange - when I click on "Software downloads" link, I am navigated directly to the section with JBCS OpenSSL downloads. Regarding to the RPM installation - do you have jb-coreservices-1-for-rhel-6-server-rpms or jb-coreservices-1-for-rhel-7-server-rpms RPM repository enabled as is mentioned in that KB? You can check with: 'yum repolist' command.
Note: basically you can use libraries from any decent OpenSSL version as it should still work. But only those OpenSSL libraries that are provided by JBCS project are officially supported and tested.