GCSES

It depends on your school and how many they will timetable in for you. But most people take around 9-12 I think, some can take more.

You can take more definitely.The minimum is 5 as that is what is required by unis at least.

I'm pretty sure that you need more than 5 GCSE;s to get into uni? Might be wrong but I thought uni's look at your best 9

Well, most sixth forms say you need at the bare minimum 5 A*-C grades to get back in. So, if you need that much to get back into sixth form, AFTER YOUR GCSEs, that's what you'll carry forward for uni. But, I think 5 GCSEs (Eng Lang, Maths, Bio, Chem, Phys are normally the requirements) are only taken in exceptional circumstances for the very few people.

I think the 5A*- C is more about the grades you achieved and not the number of GCSE's you take if that makes sense. The vast majority of applicants will take more than 5 GCSE's and thus when applying to uni you will likely be at a disadvantage if you only took 5. But I guess it depends on the uni/your situation