I think you just answered your own questions. Using a scrap piece will help you test the stain and your own technique. From memory, on the ES, I think I started from the inside to the outer edges. That also would help prevent runs down the side.

A little residual colour will always come off on the first coat but I've had nothing to worry about. Just make sure your coats are even before you start to oil. A thicker first coat won't hurt either as it will soak in more than following coats. The trick to colour and oil coats is getting them even.

Despite what the bottle says, Tru Oil goes amber over time. So you are right, blue and yellow equals green. I haven't use other oil so I'm not sure.