Truly possible, but my odd English can be misleading, too 
You can keep freewheel and brake discs - but you need a 4-notch standard BMX tool for the freewheel and a Torx T25 bit (key, screwdriver) to mount/unmount.
The Vans are overkill and actually too wide (“dish” required) and these rims are not any longer available.
Sure. Just to repeat - small modifications are required regarding the magnet catch function.
Exactly, no special “dish” necessary.
No idea, you should ask them!
All I can tell is that in Germany are zero 16" wheels in stock, only some parts to make them.