Watching many tutorials, I saw one where they used wax paper to pick up and transfer the leaf sheets. Perhaps that will help. I haven't tried yet myself.
Yes you can mix two or more metal leaf even in the same application of size. If you are leafing over top of leaf, then you will need to reapply your adhesive size. So go ahead and have fun!
Metal leaf application always has cracks, edges and small reveals. The coloured background adds depth to the colour of the gold. It is a traditional technique.
