A user handbook isn't going to teach you how to ride a bike. Power settings and gears are as you would expect, the higher the power setting the more assistance you get, the higher the gear number, the higher the gear ratio.
Rather than going to the expense of going 11-speed at around £450 at the best prices I'm going to try a smaller sprocket first. I've just ordered a 19-tooth sprocket, that's down from the standard 21-tooth. Hopefully I'll still be able to drag the bike up the steep bits.
I'm currently riding with normal pedals on my e-bike after many years with various clip-less systems and shoes and I don't miss them at all. But they must help to some degree if you're really going for it.
Yes as I remembered, with the vertical drop-out you could easily add a tensioner if you felt the need, on my horizontal drop out I had to remove a tab from the tensioner plate.