Google's not free. It's $25 plus they skim 30%. There support should be better. That's the only gripe I have on Google over Apple. Apple's support is not bad (it at least exists and you can actually talk to people).
Regarding the screenshots. This isn't an issue, this is by design. It's not great design, but...yeah.
If you want the game to be listed as made for tablets you need to upload tablet screenshots and have max API at 19.
What happens is the play store is supposed to take a look at your device resolution and show the screenshots that match your device. I think what really happens is that those get shown first. At any rate I think I've always seen duplicates. It's annoying and I'm sure they're working on improving it.
Same thing happens to the big guys.
What you could do is have different screenshots for the device sizes, not just different sizes, but different images. That way you could at least give some variation. I just duplicate though.