Unfortunately, there will always be a multi-classing penalty of sort. (I'm one of those people who code and design for web development, but masters neither.) For design, I've learned that the essential trait is to set one's mindset and philosophy on problem solving (as well as have an intrinsic taste for art). For code, I believe it is quite similar. Except that standards and practices constantly change. As a designer, it is your goal to meet and deliver these standards. Personally, I find it hard to be extremely good at both although I still consider myself competent.

My personal answer your question:

1. Some companies/start-ups value designers who have penchants for design while still being technically competent. e.g. someone who is familiar with grids, typography, art movements. While at the same time is familiar to version control, knows the basic structure of an app and the ability to build it single-handedly. Although I think that they serve a better role as project managers.

2. I have yet to witness one. If ever I meet one, I'd like to know how they were able to balance their daily information consumption.

edit: spacing