Right you are.
Carry on. :|
Is each large square section of the map 128 blocks? I tried to count them on the screen but my eyes started bleeding halfway through. Assuming they are, it looks like about 10 squares of land to cover, which means 1280 pieces of rail. :| I have plenty of iron so I could probably do it, this is going to be a nice big project.
So I should be going: Powered Rail > 32 (31?) Rail > Powered > 32 > Powered > etc? What's the best way of laying it over water, just on top of a line of blocks sticking out from the shore?