I’ve seen the prototype with the movable keyboard and padders, but is the keyboard going to be removable and replaceable with merely the padders for a flat and keyboard-less experience?
I don’t think this is some top secret stuff to hide but if so then sucks for me I guess.
An other question is, are there improvements to the trackpad over the FW13?
Also do not ask why I want to do this, I have my reasons that are very niche that most people cannot imagine.
You ask them not to keep secrets 
Yet you keep secrets yourself! 
Not directly. Each of the small side spacers has two connection points at the bottom side of the module, but there’s not a full row of connection points on the laptop. They’re mostly near both sides as Framework expects you to use a large keyboard module in the middle that acts like a “bridge” between both sides. You could of course mill or 3D print a flat module that has the size of the keyboard module.
I think OP’s niche reason is that they are stuck with a 40% ortho mech keyboard and can’t use a regular keyboard anymore. Well, I have the same problem 
and being able to swap the full keyboard for a flat surface would be very handy.
The system detects whether the input modules are fully populated, but you can bypass the checks and boot without all of the modules. A full-width spacer part is not something we’re currently planning to develop, but it’s certainly something that a third party could create, along with the necessary signaling to tell the laptop that the modules are all populated.