Will the lotteries have a chance of rollover if you set a ticket amount 50, and only 2 players buy 5 tickets?

I don't exactly want a player to win the lottery every time, sometimes it should rollover if a ticket is drawn that a player does not have.

Can "raffle" lotteries be created?
Player buys tickets with econ money, and can win an item at the drawing?

That's exactly what ticket amount does. So in your example, there would be a 10/50 or 20% chance of a player winning the lottery and a 80% chance that the lottery will rollover and reset the timer.