Projections... http://www.progonos.com/furuti/MapPr...f.html#Oblique and the next page on that site... http://www.progonos.com/furuti/MapPr.../cartProp.html

You seem to have a good handle on the rest of it. And if you want 9000 x 6000 to finish, according to 50% resize, you'll start with 18,000 x 12,000. It is big. Save often. =) It can be helpful, if your system gets sluggish working at that size, to create a snapshot/flattened file of the current state and then work on the next layer above that, then when you're happy, bring the new layer back into the mother file with all the separate layers or simply save it with a different file name ( Layer 7_Rivers ).

When working on something for print, it helps to work on it real-size so that you don't focus on a little detail at 100% zoom and then figure out that you either can't see it or it looks terrible at print scale (it's rather frustrating). Labels, for instance, can look legible on your screen but downright tiny on paper. I believe there's a PS function that allows you to have two working windows of the same file open, so you can always view the effects on the 'big picture' while making minute adjustments zoomed in to the other, without having to zoom in and out all the time.