Hi,
Make sure you have the updated copy of the module. On the inside front cover with all the legal text, the lower left corner should say revision 1.
On the humanoid-centric - yep - in a city. The second module has more variation.
For the dazing encounters;
first encounter - the dazers are only activated after the main part of the battle is finished (unless the heroes go outside). This is a two-stage encounter. The 2x3 guys don't necessarily have to employ those attacks either. As a DM, part of their attack could backfire - rooftop collapses or snow dumps down - and don't forget collateral damage. There are many ways to turn those attacks around.
second encounter - that one is intended to be tough. The idea is for the bad guy to get away. The Solon Lore on page 10 can also help the party avoid things. I suppose it should add something at the DC 15 level about 'their bright gaze forces one to pause in the presence of such righteous might'.
White Wyrms - 1 encounter (save ends) and a 2x1 dazing till next turn is about right for the encounter.
Low DCs: Absolutely. The post-errata
DMG table is being used. After playing for awhile, the lower DCs fit a lot better in my experience. Now Skill Challenges can be successful about 70% of the time with my crew. That is huge, because many clues and hints fall out of the successes. Of course, all these numbers are suggestions. I find the story to be more important and the lower DCs help to keep it on track.
Remember Flaganus is the 4th encounter without rest. They have probably exhausted all their dailies. Also, double-check that he has his double-attack power and ragesian scythe. Those were dropped in the first release. I've also started playing him as leaping over the heroes at the door to gain some space outside - taking an opportunity attack or two in the process. I expect that he will not experience any dailies from the heroes and never forget the 2 Action points! He can do a healing surge as well.