Import Participants into Project via API

Hi all, Newer here to Qualtrics but not entirely new to using API's with python. Is it possible to import participant files into a single Qualtrics project? I can't seem to find the url to send a request to with the required parameters. Any help on this would would be much appreciated. I came from a system that used project level API tokens that would direct them to a specific project automatically. Another thing I am curious about is the limitations. How many participants could you upload with lets just say 10 additional fields beyond the required fields in a minute or in a certain time frame? Thanks in advance!!!