(1) Sorry, I got confused. Well, I looked & could find nothing helpful about PDFill. Sorry again. And I'm dead in the water on the Store problem. But, if I run into anything, I'll definitely be back.
(2) OK. Windows Defender does well enough with the test virus, just a tad sloppy & oddly inconsistent in its report. I wish it ended up saying "threat blocked" in all cases. But Microsoft continues to work on Defender. I think we do well to trust it. Definitely, I've got no more EICAR in the computer, except 4 shortcuts. Three go to the MSFT site explaining EICAR & the bottom one to the EICAR test site...
Good luck, & keep us informed.