How to Get an A* in A-Level Maths

If your probability of winning a point on your serve is say p = 0.5
And your probability of winning a point against your serve is say q = 0.5

What's the probability you'll win a match of tennis? (easier than it looks)

Then what about if you're more likely to win on your serve and less likely to win on your opponent's serve
say p = 0.6, q = 0.4. What's the probability now? (still easy enough)

And what about if you're better or worse on the pressure points - break points, set points and match points for and against you? (we can make it incrementally harder though!)

Suppose you're a reasonably good player - you usually dominate your service games, you return a good few winners, and you play reasonably consistently throughout a match with no weakness on the pressure points - maybe a weaker backhand than forehand - which area of your game do you most need to work on in order to increase your chances of winning?

If you can answer that last question intuitively, you could make a good tennis coach ;)