How will I do on step 1? And how do I know how I will do? What’s the deal with these new NBMEs?
Hard to say. Being that they are new, the data available in the places like reddit and SDN that would establish a correlation between them and actual Step performance is still pretty limited. That being said, in my experience as a test taker and working with students, the old NBMEs tend to underestimate performance slightly (5-10 points or so) and the UWSAs tend to overestimate it (10-20 points or so).
THAT BEING SAID, take all with a grain of salt. There seems to be huge selection bias (because people are less likely to want to tell the world about a performance they’re not proud of) for all of the internet-based survey-derived formulas that people have attempted over the years, so I discount those, and the few attempts that I am familiar with at establishing a more empiric correlation (I’m remembering one that U South Florida did a few years back) showed a weak correlation at best.