[EricH]

1) It is strictly illegal for the Analyst (or Feeder, or Drivers) to be an adult. I'm not sure of the penalty, but I would presume some form of practice-day warning, followed by various cards if continued (under Tournament rules--egregious behavior).
2) The Coach (Mr V, this is the proper term still) may be either an adult or a student. Team's choice. FIRST has specifically declined to make that decision. (These guys are easy to separate from the other drive team members--they have a unique button. IIRC, it's got a colored dot on it.)

If you think that an Analyst (NOT a Coach) is a post-high school adult, bring it up to the refs or other event officials. They'll do their checks or whatever they need to, and they'll come up with the answer of "they're legal" or "they're getting legal"--they just might not tell you what that answer is.

Regarding your point 4: Dave Lavery (who is a member of the FIRST Advisory Board, to my understanding) has made the point at numerous Kickoff events and posts on Chief Delphi: Teams that are competing without mentors are missing the point of FIRST. The idea is that students work with mentors to design and build these complicated machines that we call robots. Not mentors work without students. Not students work without mentors. Students draw inspiration from working with mentors. How they work together is left to the teams to determine individually.

Mentors+students design, build, test, and program the robot in not enough time, with not enough budget, and possibly while driving each other slightly crazy. The mentor-student combination is quite possibly one of the most effective out there--witness the powerhouse teams, most if not all of whom use that model to great effect on and off the competition field.

To answer your other points:
1) Not valid, as Analysts are a student-only position. If you're thinking of the Coach, I'll get there in a minute.
2) Not necessarily. Maybe the rest of the students didn't want the job. Maybe the team cycles drive teams, with an A and a B team, allowing more students on a drive team. Maybe none of the students wanted the tremendous pressure (YOU strategize on the fly for 2:00 and communicate the strategy to your drivers, your partner's coaches, and the Analyst for the alliance!). There are a variety of reasons on both sides.
3) Does it now. You're assuming that mentors have better judgment. It would probably be more accurate to say more experience, but we'll let that slide. That isn't always the case. Also, it's not uncommon for a student coach to beat a mentor coach. It's all in the strategy and the execution. Remember that pressure I mentioned earlier? Pressure can really break someone.

On to your final question: Because FIRST specifically allows mentors to coach as the Coach, no, there are no asterisks for wins that have a mentor in the Coach position on the drive team. There are questionable wins, yes... but they're not from the makeup of the drive team. They tend to be from somebody on the field crew making a large blunder (like calling something not scored when the rules said it should be, and then replaying the match 15 minutes later instead of fixing the score when it was brought to their attention).