Wow, you sure didn't waist any time! Actually, mist and vertical edge notwithstanding, I think you've done a pretty good job on those mountain ranges, given that you're working with random cloud patterns. I'm not quite sure exactly how that vertical line in the south-west mountain ranges showed up. My only guess might be that perhaps in attempting to move all of the mountain ranges, you might have accidentally moved one of the layers as well? As for the off-set snow caps, I experienced the same issue in making my map. What I did was simply to use the eraser, smudge and blur tool on the snow-caps layer to try and manually get the snow caps in the right places. If I were to do the map over again, I would do things differently. Instead of waiting till step 20 to erase/move the already finished mountains, in-between step 15a. and 15b. I would have moved the resultant cloud patterns where I wanted my mountain ranges to be. If I had done this I would have saved myself a considerable amount of time doing "touch up" detail, since steps 16-19 of mountain creation would have be based on the "planned" mountain arrangement, not the "random" cloud generation. So, if you still have an existing duplicate layer of the mountain layer prior to step 15, this might be another option available to you.
Over all this is looking great so far though Geoff. Looking forward to watching it progress. By the way, if you're looking for ideas for how to do trees, a friend and I are currently collaborating on a tutorial on the subject. We haven't finalized the tutorial yet, but I could send you the beta-test tut if you'd like. If you're interested, just email me at firstname.lastname@example.org.