2) It's pretty normal for people who give you money (be it a loan or an equity investment) to get their money back before you do in event of a sale.
Imagine the situation where you raised $5m for 20% of your company and then the next day you sold the entire company for $5m. You'd get $4m and the investor would get $1m, you'd be very happy and your investor very unhappy.
Hence no rational investor would give you money without a clause that ensured that in the case of an exit that they had priority upto the amount they invested.