Uni student from the UK

Ok here goes:

1) How important are extra-curricular activities? I currently play sport at college level and outside of uni for a local club, and am planning on going abroad to volunteer for a month. Should I try and reach committee level of a big society (ie Marshall, Consulting etc...)?

2) Will attending an IB spring week by beneficial for my application to an MBB for either a Summer Placement or later on a graduate role. (I am going into the second year of a four year course so I am eligible for first year insights and spring weeks)

3) I've looked around and have found lots of resources on case studies and examples but I have ZERO knowledge about these currently. Is there any resource which teaches the very basics about how to handle case studies?

4) To what extent is networking important in order to land a summer placement or a graduate role as a business analyst at MBB?

5) Is there any big advantage to getting a 1st over a 2.1? To get a first will require a LOT more effort and I am unsure if this time and effort could be better placed on extra-curricular activities instead to build a better CV.

Thanks in advance.