I don't understand the second question, but as tot he first question re: feats and Ruins of Symbaroum for 5e, the answer is that when a third party, in this case Free League, produces content for 5e, they are not using the PHB as basis but the 5e OGL's System Reference Document, the SRD. The SRD is a very stripped down representation of the 5e rules, designed to provide the mechanics of 5e for developers to build whatever they want on top of it. Most 5e races, subclasses, feats and backgrounds and many monsters and spells and magic items aren't in the SRD.
The nature of the SRD is made more clear in its FAQ where it specifically touches upon the SRD's lack of backgrounds and feats:
Why does the SRD only have one background and one feat? Why do the PC races not include all of the subraces? The goal of the SRD is to allow users to create new content, not to replicate the text of the whole game. We encourage players, DMs, and publishers to come up with their own backgrounds and feats.
In other words, technically third party books like Ruins of Symbaroum for 5e aren't designed to be integrated into a WotC 5e D&D rules as written game. In other words, beyond the mechanics of the base classes, the book is designed to replace the player options in the PHB, not expand them. Yes, many folks will kitbash a third party book with the WotC RAW with varying success, keep in mind that many of these works are actually designed to play differently than what WotC developed from the SRD foundation.
So as designed, you're supposed to use the feats in the Ruins of Symbaroum book.