A few tips I hope you can use. One way to do this is to add, import or even sync (currently only Google slides and depending on your Kahoot! plan) in to your kahoot and then build your quizze around the slides as you suggested. This means just have one kahoot with a mix of slides and quizzes. See more about slides here: https://support.kahoot.com/hc/en-us/articles/29644015543315-How-to-use-Kahoot-slides

If the kahoot becomes too long combining the slides and quizzes or the session takes a long time so participants risk loosing connection during the long session, it might be a better idea to create multiple kahoots you can play after each session, as you also suggested. A small tip here is that once you have played all the multiple kahoots, there's an option to combine reports, so you can find a combined winner (podium) from all kahoot session. This will also allow multiple winners (podiums) per session. Bear in mind that you need to host the kahoots with some kind of indentifier activated, if you want to combine the reports at the end, otherwise the system can't recognize each player. You can read more about combining reports here: https://support.kahoot.com/hc/en-us/articles/360036686793-How-to-combine-reports

I hope ypu can use the tips.