Clarifications:
1) Stop worrying so much about Step I until you are at least partway through 1st year, preferably all the way through.
2) The max score is higher than 260. The highest scores I have heard of, from several people, are in the 280's. Never heard of anyone with a 290 but perhaps it's possible. Don't know the maximum. The NBME and USMLE folks keep this under wraps and never say exactly how things are graded. I know for a fact the max is higher than 260 though for reasons stated above.
3)A 99, the top 2 digit score, correlates with something like a 245 or even lower. You can't get a 100.
4) THe average is 218 or so, the 3 digit for passing is about a 182. Standard deviation is around 20 points, use your statistical knowledge to figure things out. Thus, everything above 240 puts you in pretty select company. For competitive fields, a lot of people are in select company though. 2 digit score is NOT a percentile.
5) Anything above 250 is generally considered "fantastic" and perhaps equivalent to a 40 MCAT, but don't quote me on that.
I don't know the answer to your "how many questions out of 350" thread. There are a number of the 350 questions which are not actually scored, they are "practice" or "test" questions which are designed to see how people do on them, experimental type. My theory is that there are 350 questions, 50 throw away, and the maximum score is a 300, but I'm probably wrong, because theoretically, with the # of people who take this test, a few people should get perfect scores, like the SAT.
In terms of matching, people here got their #1 choice in pediatrics with board scores below 190. I have heard of some programs in other specialties that have minimum board scores for granting interviews, but this is often not true. That being said, I received some interview requests when all the program had was my board score and my demographics (things are transmitted separately). In general, top students with good resumes have good board scores as well, so be careful about ascribing success in matching with high board scores. High step I (>250) with mediocre grades and poor LORs won't get you anywhere. It's all taken in context. In my humble opinion, in the comparison between MCAT importance in getting into med school vs USMLE importance in getting into residency, MCATs and med school win. Residency applications have more important things like LORs, your transcript, your extra things (research, papers), and your interview.
**edit**Step II often doesn't factor into residency. Depending on when you take it (usually after 3rd year but before graduation) it may show up before match day at the programs you are interested in. If you do well, it can help of course. Doing poorly, not so much. So many people take it fairly late (december) and then decide whether to release the reports to their programs before match day.
