1)
けど is also OK.
I didn't make everything more formal. I just unified the level of politeness (必要です, いいと思う, かもしれない).
2)
そうする前に is also OK here.
そうする前に can be used for the both cases.
3)
起こる and 起きる are interchangeable in this meaning "to happen". 起きる tends to sound more colloquial, imo.