With the usual caveat that "it can all change so don't consider it a done deal", the answer to all your questions is to look at the information guide for last year. The courses rarely change much. Disney re-uses the event guide website, so the guide for 2023 is long gone, and I can't find anything from Wayback Machine, so you will have to do a search to see if anyone archived it. Else, here's 1 link where you can get an idea of what 2023 was like.
https://noguiltdisney.com/2023-prin...-course-maps-event-guide-waivers-and-corrals/
Also, check out the thread for last year's race. Here is a link to where some event guide details were published.
https://www.disboards.com/threads/princess-weekend-2023-feb-23-26-2023.3873904/post-64597161
As for "what might be closing in the parks", if you mean before/during the race, the answer is nothing. The races don't affect park offerings since they start early.
The event guide for next year's race won't come out til a few weeks before the event.