Free 3rd Party Software, such as "PDF Mac Master": Opinions on methods to address safety and compatibility? Anyone??

I have a general question about free 3rd Party software. I was researching a technical question about Exel for Mac, and a site answered it beautifully, perfectly. The site/company offered a "handbook": a free one. Just download the app "PDF Mac Master" by a company called "New Media Holdings". Then in researching compatibility and safety for this app, I found an article about many free mac-friendly apps that seem extremely useful.

I found a forum non-answer answer to a question about the safety and compatibility of "PDF Mac Master". The advice:

Look it up in "Roaring Apps". PDF Mac Master is not listed in "Roaring Apps", and given THAT'S NOT AN APPLE SITE, I'm not going to download any 3rd party software not specifically blessed by Apple.

So my question is two-fold:

01. Again, where do I go to figure out if "PDF Mac Master" by "New Media Holdings" is compatible and safe with my mid-2009 macbook pro running on Yosemite, yes Yosemite? Call Apple Support? Maybe it's a very new application.

02. I assume this forum is the best way to check on FREE 3rd applications, and it was a forum answer that led me to "Roaring Apps", which did not answer my question (#1 above) whatsoever, and I thought "is there not a similar "tool" in Apple Support like "Roaring Apps"? Why not? So question #2 is there an on Apple-site chart or tool that provides safety and compatibility for major free 3rd Party apps? Yes, I have an anti-virus program, Bitdefender for Mac. And I don't think I made the best choice in selecting it, except I thought I was simply upgrading the free anti-virus software Apple Tech Support endorsed, so . . . I'm still devoted to Apple and Macs, but again, what is Apple offering in terms of pre-screening FREE 3RD PARTY APPS? AM I BLIND?