A couple things first Trans-am would be terrible for Graham as his Suit has a finite power supply unlike the real solar furnaces. So if he used trans-am once it runs out of juice he better be on the ground or he's going to die from simply falling. It only works with a real GN drive because they constantly produce particles so it never will completely run out.
I've been calling Seravee splitting into 2 Gundams since we got to see the second face so zero surprize on that front.
As for the singing while I can't say I'm to happy about it the reason Setsuna was hearing it was because he was in Trans-am with the double-O raiser so his link with Maria was amplified and that is why they all heard the singing not because they were singing that loud.
The new opening is at least acceptable though no ending this time around I hope kiddies singing isn't used for a ending in the future.
On the downside now Setsuna has a way to fight without killing aka using his Gundam to amplify childrens singing and causing everyone to stop fighting. I REALLY hope they don't go anywhere near the route in the future but it was heavily foreshadowed in this episode.