I prefer in-play staking rather than pre-match type of staking in sports cause I would like to see the condition of the players I am betting into. I'd like to see if the player I'm rooting for in that team looks well, and active just like how I know them. Although, I know that the probability of that team winning is equal to the percentage of the opposing team winning. It still gives that satisfaction, and contentment that you place your bet based on your own decision, and principles in betting. 

For the 2nd question, Pre match type can be more risky cause they can be emergency changes in the sports that can diminish the chance of the team winning.