Any grander plans for this setting beside this trilogy of Skyward?
Any plans for that other work the Skyward is connected to?
Is there any connecting stuff we should be on look out for?
Let me get this trilogy (which will actually probably be four books) done, and then I'll worry about that.
No other plans for the work this is based on right now.
As for connecting stuff, it will become very obvious once I start using some technical terminology. I said elsewhere in the thread that chapter 17 will make it very clear for those watching. Other small connections exist through the series, but more in the second book.
As a follow-up, will the fourth just be adding onto the end (i.e. it's a quartet), or will it be tangential, similar to Mistborn: Secret History (i.e. a trilogy + another book)?
It will be a quartet. I did my normal thing, writing the first book as proof of concept to myself, then sitting down and really hammering out the series. When I was done, the story beats worked far better as four books than three, so I will probably write it that way instead.