The cloth is very thin and has enough space between the keyboard and the screen. It even protects the screen a little because the keys don't touch the screen. 

About 4m/13ft. 

Dear Customer, Thank you for your question. Please check the following steps to setting the focus: (Do not look at too close objects) Step 1. Cover the right objective lens with your hand or close your right eye, rotate the central independent focusing wheel until the image in the left eyepiece is sharp and clear. Step 2. Now cover the left objective lens or close your left eye, rotate the right eyepiece focusing wheel to adjust the diopter of the right eye until the captured image is sharp. 

Yes these lenses should work fine with a Nikon G adapter to Fuji X mount. 

No