What do i use to attach an ikea table top to storage facilities. links attached

You can always use a masonry grinding wheel and a level, but be warned, there will be a LOT of dust! You'll want to seal off the room from the rest of the house, open the windows, put fans in the windows, wear goggles and a respirator. They sell shrouds that you can hook up a shop vac to the grinder to get a good bit of the dust, but it's still bad. And at that point, it might take you 2 to 4 hours. I leveled some high spots on my basement floor and man, what a time waster! You may be happier if you rented something bigger than a grinder, or used something like below - the bonus being, if you used aggregate, it'll shine through after grinding.

You could also rig up a sled if you would like, where you attach something flat to the back of your grinder and then run it along something flat and level independent of the table surface, like below. Unfortunately, I don't think they make diamond cup bits for routers, but you might be able to use a diamond hole saw with a 1/4" shank if you want to use a router/sled method.

1/4" tempered glass should be fine. It's considerably stronger than the same thickness of normal glass, and also much safer in the event that you do manage to break it.

LED (or any other light source) into a glass sheet is normally injected at the edges (the LEDs being built into the table frame) - but it may not be all that exciting on a clear glass sheet (the ones you linked to were heavily textured - it needs to at least be frosted on one side for much light to get out.)