So from my perspective from my undergrad (Dartmouth):
1. I'd probably pin our grades somewhere between "neutral" and "slight inflation". Grades below a C in a most pre-req classes are almost unheard of, and grade inflation as a whole is generally rampant (example: The cutoff for Phi Beta Kappa, which is top 10% of the class, is now a 3.94, wow!). That being said, grades in the most "stem-ish" areas important for pre-meds are generally lower; while the physics classes are running around an A to A- median, the bio and chem departments have been the most reluctant to up grade inflation, and pre-med relevant classes in those departments continue to hover in the B/B+ range. Those also happen to be the lowest medians of any course in the school; I do not know of any course in my time being there that has a recorded median at a B- or lower. Finally, Dartmouth has 1 more unique thing on its transcript other colleges don't: medians are published as well. I have no idea how this helps applicants, but its on there regardless.
2. With Dartmouth, it's hard to really say if it's collaborative or cutthroat from a premed perspective (it is DEFINITELY cutthroat for anyone trying to work their way into finance or consulting, which also happens to be the most sought after profession in the undergrad body). I generally stayed away from other pre-meds during my time, not out of dislike but just because I wanted to do more than just thinking about being pre-med all the time.
3. The HPP office has a wonderful set of advisors, and advising is open to everyone from the beginning. I honestly regret not using them more and earlier.
4. Again, in part because of the small school environment and the relative lack of pre-med interest, as far as I'm aware the school gave everyone a committee letter who applied.
5. Research money may as well come from the trees at Dartmouth; there are a lot of professors and not a lot of grad students so it makes it easy for students to jump at research. There is also a very robust shadowing program at Dartmouth Hitchcock as well. Volunteering opportunities aren't nearly as well laid out (especially in the context of clinical work) but still many opportunities nearby; I personally worked at DHMC and volunteered at the VA hospital in White River Junction.
If you don't mind me asking, is there any specific reason why you're asking for insight on schools in this way?