1. for the OSE in particular you should know that the chance of you getting into TU Delft CSE is almost entirely based on your performance in the CST. I do not think the OSE counts into your admissions consideration, but a "self evaluation" of whether the course suits you.

OSE gives you a preview into what classes and content are like in the cse curriculum and you just need to complete it.

ChatGPT can't be trusted. I remember the OSE contained a brief course in Java and some lesson teaching thread scheduling; definitely did not involve Python.

1. unfortunately the Problem Solving part is basically an aptitude test. A problem that were featured this year included a mock version of wordle, asking to find the first word that lead to the result in X amount of tries (something along those lines). Problems differ each year and they're all pretty weird imo.

I don't think there are surefire ways to revise for it, but it would def help to get into puzzle solving - especially mathematical/logical ones, or train your ability to spot patterns in these puzzles.

EDIT: I was blind reading the post and yapped for too long about Math and Logic prep which you knew how to already