1. The newer if available. Personally I've never read either but if I had to chose one to read I'd always go with the newer.
2. I don't wash them.
3. Consistancy. Don't over-think the process or you'll take all the fun out of it. Try different things, if you don't know if it can be done a certain way, try it and see.
4. Personally I press to the side. Some things say to press open to make them lay flatter. Some quilters press open for the same reason. It, too, is a personal choice.
With most things in quilting there is no absolute right or wrong---just do what works for you. Okay, there are a couple like "Keep your finger tips out from under your rotary cutter." and "Don't steam iron sitting down unless your bra is heat proof" and a few like that but most things are personal choice. Oh, I almost forgot the most important and most ABSOLUTE RULE: Have fun and enjoy.