Pentax smc DA 18-55mm F3.5-5.6 AL WR Q&As

Hi ! I just bouth a Pentax 18-55 WR. You can see it here: https://www.ebay.it/itm/SMC-Pentax-DA-18-55mm-F3-5-5-6-AL-WR-Lens/332913988407?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649 It didn't arrive yet but it will soon. As you can see in the description cover for the filter window is missing. Do you think it affects the weather resistant feature? Moreover in the first and in the second pic, magnifying them, I see a little mark heart-shaped. What is it in your opinion ? Seller...

I have a k5 that seemed to miss focus a lot.  I came across a beal on a k50 I couldn't pass up on so bought that.  It seemed to focus better with the 18-55 WR.  This evening I was playing around (inside, low light) and was very disappointed in the image results.  I compared them to my small sensor compact xz-2.  The xz-2 looked better.  I tried manual focus on the k50 and was able to get much better shots.   Is the focus control, or logic, in the lens or the camera body? I've been thinking...

I know what the differences are between DA and DAL, but in the case of the 18-55 WR it seems to cause a large difference in price. Is the quick-shift focus mechanism so complex that removing it allows a big price drop? Or is this large price difference just a marketing ploy. But why would Pentax be pushing people in that direction? Any insights appreciated. --Tim