Ambiguity on the job & dealing with multiple demands

I actually thrive in a job with some ambiguity/unpredictability, sometimes conflicting demands and general direction --as long as I'm equipped with skills to dive into problems and solve it properly, handle on the spot clients or walk into meetings that have a loose agenda with people who I have never met/seldom work with often.

I actually love thinking on the spot --as long it doesn't mean a costly mistake!

At this time, it's frustrating to be in a project where there is a mishmash of expectations among team members. Plus we have new team member who just joined. And there's not much I can do since I'm not the project manager. I can only suggest, listen to other members, etc.

Do you work best with clearly defined structure, best knowledge of content that you use in your job, etc.?