Transfer student questions for IB recruiting

I transferred from UC Irvine to USC this year because I want to work in Investment Banking. I was accepted to start in Spring 2023 i.e. Jan 2023. Now, I have 6 months of free time and I think I might go study abroad. 

I had a couple of questions: 

- Should I mention that I transferred from UCI to USC on my resume/ Linkedin or should I just put on USC and the graduation date? 

- Should I mention Study Abroad? 

- I had quite a few leadership experiences at UCI. However, given that I would be a new student at USC, I won't have that. Should I mention my positions at UCI? 

- So recruiting for Summer 2024 (my junior year summer) at USC would begin in Spring 2023 (the time I would start), would it be a significant disadvantage if I do not have leadership positions/ involvement in clubs even if I were to network quite a lot during fall? 

- I will be study Math and Economics and not Finance at USC, would this be a disadvantage when it comes to recruiting? 

I appreciate the help. 

Thanks!