Can you make a NON-Attribute based presentation as required or mandatory? for example, a Link

There is noting built in unfortunately. You could create an advisor that has built in rules to validate them and prevents saving. This would essentially be your own "RequiredLinkAdvisor". https://rsjazz.wordpress.com/2012/11/01/restrict-delivery-of-changesets-to-workitem-types-advisordelivery-of-changesets-associated-to-wrong-work-item-types-advisor/ shows an example and leads to other information you would need. This is a real effort, due to the complexity of the API and doing extension development.