This is a bit difficult to answer. I apologize in advance, because there are several things to consider.
In response to the first question, teams are set up based on specific procurement projects, which help find the resources needed to increase the likelihood of successful procurement approaches.
As far as the approaches go, we have used them in a half-dozen cases. In these cases, the agile process is intended to work very closely with the customer or the department that we are buying the goods or service for. In our case, it's usually IT services.
Essentially, it's to give us the opportunity to deal with multiple vendors that produce prototypes. We then try out the prototypes to determine which ones might work for us. Then we choose the approaches we might use to move forward. The vendors involved in the process are aware, from the beginning, of the approaches that will be used.