The 'shelf' is that horizontal flat area just above the grip where the bow handle has been cut out to allow the arrow to line up with the string. By placing a thin pad of felt or similar material on this shelf, it then functions as the arrow rest, or platform, from which the arrow is launched. For instinctive shooting it can be advantageous in it's simplicity and the fact that it places the bow hand, arrow, and eye in as close a horizontal plane as possible, which is a good thing for that style shooting. On the down side, the feathers rub against the shelf and handle riser as the arrow departs the bow which will influence arrow flight to some degree. I do not find that plastic vanes work in this setup.
Alternatevly, you can add a commercially available 'arrow rest', which typically is glued to the vertical side of the handle riser an inch or so above the arrow shelf. This allows clearance for the feathers above the shelf and a slight clearance off the vertical riser, and permits the use of plastic vanes if you desire to use them. An add-on arrow rest will typically give a cleaner departure of the arrow from the bow, and perhaps improved arrow flight over shooting off the shelf, at the minor expense of introducing a gadget to your otherwise simple setup.
Regarding the gluing of feathers to carbon arrows, you can, just make sure the glue you use will adhere to carbon shafts. Some glues are designed for wood or aluminum, and will not hold long if used on carbon. Hope this helps.
