I use the ET Lite for my bottle caps. You can get it at Hobby Lobby or Michaels. I always get the 40% off coupons on my receipt at Michaels and use that for my big purchases like the ET lite. At my HL it is on the glue isle (like where the hot glue guns, mod podge, etc.). It will be in a box. At Michaels it is also on the glue isle, but it is on the bottom shelf.
If you have bought the images you could just ask the seller if you could get them in a 4x6 sheet instead of the 8.5x11. I have done that for several of my customers, but they were wanting the 8.5x11 and not the 4x6. I use photoshop to crop and resize mine.
I use glossy paper on my printer at home, but before I punch out the image I put a piece of packing tape over my image, rub all the bubbles out of the tap and then punch it out. This ensures the ink is sealed and you wont have any colors run when you put the resin over your image. I use the Xyron sticker maker to attach my image to the bottle cap, but then I also put Mod Podge around the edges of my images just to be sure that no air gets under the image, as that will make it look wet when you pour the resin over it. HTH!