- Using templates in the DOM is a standard approach used by many libraries such as the deprecated jQuery Templ library, JSRender, Handlebars.js, etc...
- As you mentioned Intellisense has gotten a lot better in Visual Studio 2012 and if you want even more you can start to play around with TypeScript by Anders (creater of C#). As you mentioned it will give you rich typing and some helper syntax around classes, modules, etc. I would imagine they didn't introduce TypeScript in a session like this in order to make the examples easier to grasp without adding too much new syntax. The barrier to entry by adding too many too things can be overwhelming for some in the audience.
- Live coding any demo is a risk regardless of the language. I thought the presenters did a great job. Demos are a tricky business because you want a large audience to be able to grock the new concepts you are explaining in a way that is understandable.