Wayland and window position/size

[Igor Korot]

Hi, list,
Couple of questions about Wayland, since more and more distros switching ;-)

If I understand correctly window positioning/sizing is based on the
compositor/window content.

1. Is there a way to select where each individual program will start?
1a. If not - will there be one?
2. I am working on the program that should start up with the empty
window - only the toolbar
and the very basic menu.
Then when the user chooses some action from the toolbar some child
windows appear.
I think such program will always start up with very minimal size,
basically the size of the toolbar
under Wayland. Am I wrong?
3. How can one write a cross-platform application that should behave
the same on the different
platforms when the developer doesn't have control over window position/size.
4. How can a developer write a program that should connect to the database?
5. I know there was a plan to respect a save/restore window
positioning/size. Is it implemented?
6. How complete is Wayland API currently in terms of window positioning/sizing?

Thank you.