One option for making them stand out is to spray over them with a gloss coat. Since you background is likely flat black this will bring them out. Another interesting trick I saw once to give the records some dimension, is to apply a thin coat of plaster and while wet brush over it with something like a scrub brush going in a circular pattern. This will leave what looks like grooves in the record. Obviously if you went this route your wouldn't do it on a flat, you would have to make sperate pieces for the record.

As for holding them up an A-frame would work, if the bottoms are supposed to touch the stage. If they are supposed to be up in the air, it would be hard to hide the A-frame. Without knowing the requirements of your show it would be hard to suggest the best way of doing this.

Dan