Slide not fully returning to battery is a common complaint. It is affected by many things, such as lube, grip (meaning limp wristing), ammo, etc, etc.... When the slide cycles, the striker is being cocked (compressed) during the last 3/8" inch of forward slide movement. That's the point where the sear catches and holds the striker as the slide continues forward. When the slide stops just short of full battery, all you have to do is bump the rear of the slide with the heel of your hand, forcing the slide the rest of the way into battery. That'll put the slide into battery and the striker will be cocked.
When you had the slide stop, just short of battery and you pulled the trigger, guess what happened? Pulling the trigger, released the striker, letting it snap forward....this action also means the recoil spring can NOW push the slide the rest of the way into battery, as its no longer working against the striker spring. YES, when you do that, the striker will not be cocked, because you just pulled the trigger, which releases the striker. You would need to move the slide rearward about 3/8"....to the point where the sear catches the striker, then you'll need to push the slide forward into battery.....THIS will recock the striker without ejecting the round that's in the chamber.
Your Q4 should improve with use.....meaning more rounds. Also need to ensure its well lubricated and you need to use a firm grip.