Remember to click on the photos to see a bigger version.
It's going to be fiddly getting these things on the planes but I think it's goimg to be a case of taking it slow and steady. Here's a shot of the decals up against a 5c piece to show the size of the smaller ones (I tried using a ruler but mine is clear plastic and didn't come out too well in the photos).
If you're looking around for 1/600 or 1/300 decals then I don't think you can go past Dom's Decals. The price is great £2 for a sheet of between 400-800 decals and postage is a flat £1 world wide if you order is only decals. My order came with a FAQ/instruction sheet and a hand written with compliments note.