Hi ls413,
I realize that you asked this question a long time ago, but it's something others may be curious about.
MBA students are able to take many but not all of the classes that comprise the MMM program. All MBAs are allowed to take courses from any graduate school at Northwestern as long as they have approval - there is an application process for this, and it should be of clear relevance to the mba degree.
Design thinking is taught through MBA courses such as (accurate as of Oct 2012) Marketing-led Innovation and Design Lab, but for really deep application and training in design thinking the MMM course is the way to go. Core elements including the Design Thinking class and the Integration projects are (afaik) not accessible to non-MMM students.
Both the Kellogg MBA and MMM curriculums are currently being reviewed, and things may change over the next 2 years so keep an eye on the website: mmm.northwestern.edu
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As for your second question, Kellogg's greatest strength is the team-focused approach, which drives all students to develop as people, leaders, colleagues and team members. Its greatest weakness is its comparative isolation - unlike HBS and Stanford GSB it is not surrounded by a huge ecosystem of top tier graduate schools so some of the cross-pollination opportunities do not exist. That said, there are plenty of collaboration opportunities available, for instance through the NUvention experiential learning projects. But Evanston is not as dense a hub of research and innovation as Cambridge or Palo Alto.
Ben
MMM class of 2013