NIH Post-Bac IRTA Application Process Questions

hi everyone! i am currently finishing up my neuroscience degree & am thinking about applying to the NIH post-bac IRTA. i just have a few questions about the application process, housing, opportunities,etc if anyone can share their input! (p.s. sorry if I'm all over the place, i have only recently started to think about options after college and am ~stressed~ thank you in advance :) )

in terms of the application process, for the resume, does it have to be one page? I am having trouble condensing mine hence why I wanted to ask. additionally, for the three references they asked for, do they all have to be academic/research mentors or can it also be previous/current bosses at non-science related jobs?

also can someone also explain the different campuses/housing to me? for some reason the website is confusing me further but I know there is a main campus in Bethesda & one in Baltimore as well. for housing, i am from the DMV area so i know a little bit about housing but if one gets accepted into this program, do most people live in the Bethesda area or in DC?

lastly, i am also on the pre-health track (pre-med) & was wondering what the benefits of doing this program are. i am definitely going to take a gap year and i am not sure about what to do exactly in it. i have had 2 years of wet lab research experience in a neuro lab & have given a presentation and will also be writing a thesis before I graduate. my grades are mediocre (pls don't flame me for this) but idk if I should be doing an actual post-bac before going into med school or if doing this program (if accepted) is also looked at favorably bc I am very interested in research and want to pursue it in the future whether i get into med school or not.