If it is any concilation after my JPM I wanted to crawl up into a ball and just be swallowed by the pavement, so dont worry!! And the numerical and interviews are pretty important so if you did well on those you should be okay!
Most the brainteasers are pretty straightforward but I applied to another department to you guys - and from my friends who intern at Finance last year (at BarCap, MS) they were not asked any brainteasers during their interviews, so you should be fine. For the CS AC, just make sure your aware of recent developments regarding CS and more broadly the world of banking. Obviously keep up with the FT, any major news regarding the banking sector. Stuff like that will put you in good stead. Also ask some good questions, these are banking professionals so ask them questions regarding the Credit Crunch etc.
Also did you work at Standard Chartered?? My friend is on the grad scheme there he loves it!! but yeh they will ask you about it, if its on you CV, prob asking you why you want to work for CS over Standard Chartered? Also just focus on the competencies, they will def ask you the standard competencies …‘tell me about a time when you failed at a task’…‘Give me an example of when you worked in a team with difficult personalities’ …etc So be pepared for those…
How did your GS and DB one go? I read you recently had your DB?