Spring week dillema

Hello folks, north african student in europe here. I managed to get 2 spring weeks @Citi/MS@IBD:ECM in the UK. This site was really helpful so a big (y) to all the contributors and other wanabe investment bankers.

I Have a few questions:
MS > Citi ? yes but why ? does this still hold if I'm not interested in PE but rather in pursuing a career in IB or going in the industry later (eng background).
What are my chances of converting these to a summer internship at both of them ? i feel that being in a non target this should be my priority(like 0 persons of my school in IBD, a few in structuring in Paris).
I Have no knowledge of finance as i only studied maths/physics/chemistry up till now. what text books should i study if i want to impress. (academic ones! i asked my interviewer at the end and she told me about some liar's poker ... )
Is the Pearl&Rosenbaum autonomous in the sense that it doesn't require knowledge in finance or accounting for example ? any input on this would be really helpful.

thank you !