[natec425]

I disagree with one of your three conditions; I don't think all team members need to be of similar skill. Particularly, I think agile practices can be very good for knowledge sharing between senior and junior developers.

As for trust and values, I might combine the two and say that members have to trust in each others values. For example, I don't want to bother to get my code reviewed by someone who doesn't care about its quality, and I don't want to put in the effort to review someone's code if they are only having it reviewed to satisfy the process. These differences in values can really suck the energy out of the process.