Yes, the pictures don't prove much, here you have to trust the author, he's spending quite some time in the heart of the events.
Pretty girls can still be crazy nationalists, that's true. The point is that if some crazy form of nationalism has taken so wide-spread popularity in Ukraine, it would be well-known abroad already. That's not the case, it seems that the only foreign force concerned with Ukrainian nationalists are Putin's medias.
Ukrainian nationalists are often overrated: their traditional message and goal is "Glory to Ukraine", anti-Moscow feeling is also strong (not surprisingly), and alas, some historical "domestic" antisemitism which almost never comes into real actions and sometimes is actively fought (Maidan now actively protects Jews from any assaults, our government has tried to speculate on this, Berkut are also mildly antisemitic - it's a common Slavic trait). What I have never seen is hate to others based on ethnicity or just being other.
From my little experience (I live in Kiev), people are organized informally and it's an amusing self-organization: a lot of my friends (including me) have been supporting peaceful Maidan with presence, money and food. Guys at Hrushevskogo do not have some formal organization, they deny access to interlocutors if they see you're unprepared for the hell at the front line.
If you have more questions, I'll be glad to answer.