Yes, I'm old-fashioned. Written reports will probably always be my preference.
- We were playing quickly. Everyone involved in each of the large games was a very experienced warhammer player with very solid game knowledge and no need to stop to consult rule books. Everyone was also on the same page regarding why we were there, and what the priorities were - we had to keep the game moving and not waste time with minor "finagling" and nit-picking over rules. The key was to keep things flowing. We did stop for lunch, but this time we kind of skipped the dinner break. Nobody really said anything about dinner, actually. We kind of just pushed on through by mutual unspoken consent. Everyone could feel the end was in sight.
- Yeah, the white wolves against the minotaurs was an epic fight. The last minotaur to drop was not actually the doombull - he fell the previous round. I think it was the unit champion, although by that point I think he had 10 attacks anyway, so it made little difference...
- In each game there has been something that tempted us to "fudge" things. Malekith's dragon failing its strength test, Gurug'ath incompetence, etc. In each case we have resisted because it felt like it would compromise the game and once you start, where do you stop? Rather than end up with an artificial, "tampered" result, we just went with the original dice rolls. It's all kind of worked out each time anyway. It helps that in massive games like this, a single disaster will generally not dictate the overall result.
- Beasts of nurgle are very tough, yes. Turns out minotaurs are pretty brutal in large numbers, too. Some of these things really need magical intervention to swing things against them. Speed of Light or Throne of Vines/Flesh to Stone would have really slowed the minotaurs, whilst Flaming Sword of Rhuin would do wonders against the beasts. In general I don't have any specific cautionary tales about such things. Most of the time such units could be handled if they had come up against more suitable opposition or magic had taken a hand. Units that really power through the enemy or prove invincible are great for the stories too. It was just dull when the knights and beasts met, since they really cancelled each other out.
- Our tables have been congested in each of the big games. It's really a practicality thing in terms of space and resources. Ideally there would be more space, but you'd then have to consider whether you needed to implement some sort of "forced march" rules to compensate for units potentially being stranded far from the action. And you might find it impossible to accommodate your table (or reach models in the middle)...
- We kept the terrain out of the middle because it does just get in the way when you've moving huge units and as you've already noted, there was already a traffic problem in the middle. Unless it's somehow the focus, terrain will really just hinder your play without adding much in return. I had intended to frame parts of the table with trees in the corners and stuff, but forgot in the heat of the moment. Heffengen is fought on a plain anyway.
- I'll consider the blog post thing, when I have a bit of time on my hands. Who knows, I guess that could happen?

Cheers!