What do you mean by threshold? Any work experience can be good for business school, which rules out no previous experience. Yes, internships are helpful, especially if they are in companies from which internships are hard to get. And yes they count, but not towards your amount of time worked (i.e. professional experience, which includes only full time work)
As for extra curriculars, the best bets are to go for a) things you like b) a diverse mix of things c) at least one volunteer position/community service.
If you go for things you enjoy (be it a business club, toastmasters, sports club, religious club) you will be more likely to do it more and to make more of an impact, which they are ALWAYS looking for.
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