Usually, the printed surface is located on the back of the glass, so the side infront can be cleaned in any established way. 
In case the glass in printed on front or both sides , it is recommended to avoid acidic cleaning products.

There are basically two methods, it only depends on the field of usage. 
In case of sticking you should srictly use neutral silicon or it can be applied with a glass spacer(which we also provide).

In case of a kitchen backsplash we always use safety tempered glass, so it can be installed either next to the cooktops.

Absolutely, as long as the quality and proportion of the image matches the quality and proportion of the chosen print surface. 

The better the quality, the better the result.

You have to consider the aspect ratio of the surface to be printed. 
(horizontal surface-> horizontal image, vertical surface->vertical image)

We recommend www.shutterstock.com for searching. In addition, we can also create unique custom graphics.