I confirm the issue with deleting emoticons, you can only delete them with the plain text editor. The workaround is fairly easy, I don't mind it.
Since I don't have any other issues, the sample from Redactor unsurprisingly didn't show any strange behaviour.
But this is on Chrome!
I've just tried the link on Firefox and I can reproduce the issue where trying to insert a line return feed does nothing. Or rather, it happens and gets cancelled straight away. The cursor goes back up. Apart from that, everything else is OK. This is using Google keyboard.
So I suggest that the issue lies with the browser, not the keyboard. If you have issues with gtp on Firefox, try to reproduce on Chrome.