First off, I don't know what the foil is. I have a feeling that it is shim stock to be used when you peen the pivot pin. In order to do a good job peening the pins, you have to put a shim between one of the blade's tang and the liners so that they don't squish together too tight. I always used one of the little gap measuring tools you use on spark plugs thats full of different thickness shims. Pretty sure I used .005"
As for epoxy, the devcon will work fine. I've used it quite a bit myself. You need to thoroughly clean the two matching surfaces and rough them up with some 150-220 grit sandpaper. It gives the epoxy a better surface to adhere to. Be very careful about what you touch after cleaning it because oil from your fingers can keep it from bonding. I always mix the epoxy in a plastic cup or something, and mix it for at least a minute. Then apply a generous coat across one peice and clamp them together (not too tight, it will squeeze too much out) wipe away the excess before it sets and then leave it for a day. Make sure you don't leave it somewhere cold either, epoxy sets through some sort of thermal reaction, if its too cold it won't work.
For the bolsters, its nice if they are still soldered/glued (I think they use JB weld or something, never thought it looked like solder when I was building kits) but its not necessary. If you do a good job fitting the scales and peening the pins it will not come off or move. You can also put a little epoxy underneath them, or get JB weld and use that.
