I'm far from a setup expert, but it's basically like you said. A lot of it just comes to how you're driving the car - it's really easy to spin the front wheels under acceleration in WTCC cars, they have quite a lot of power, so you have to apply the throttle gradually to not overload the front wheels too much (which gives you understeer). Also playing with the front toe and diff under power helps somewhat.
Again, driving style has a significant impact on this. For the car to be more stable under braking, you pretty much never want to lift off completely, apply a bit of throttle even under braking to keep the car balanced. Apart from this, you might want to make the front springs harder and the rear softer (but doing so will in turn create more understeer I believe. Also the brake balance - a lot of people will tell you to move it forward a lot on these cars, like 64 or 65 percent, but I honestly can't drive them like that, I feel like they're much more stable for me around say 56-58. Don't know why that is. But you might want to try this out. Finally, you didn't mention which year you're interested in, but I find that with the 2016 cars, I generally want quite a bit of wing on them to keep them stable, even though I lose a bit of straightline speed. 2014/2015 are more forgiving in this regard.
But again, note that I'm far from being an expert, and I'm also not the fastest guy around here, so take it all with a grain of salt.