Do all the stars have planets?
No, there are some stars that do not have planets, either due to the way they formed, or because of their proximity to other stars. After all, there are rogue planets that do not have a star to orbit, so it stands to reason that the opposite would be true as well.
Some giant stars that formed very quickly and burn very hot would have blown away their planetary disc before any planets could form. Likewise, stars that form close to other stars may have their planetary disc (or even planets) pulled out of orbit by the gravity of their neighboring stars.
It's even possible for older red giant stars to have consumed their planets - this is the fate that our own planet will eventually suffer in several billion years when our sun grows to a red giant. The surface of our sun will grow to the point where the outer limbs of the sun will actually reach the area the Earth is orbiting in now, but that won't be for 5 or 6 billion more years.
We cannot know.
The methods we have for detecting the presence of planets require that we lie close to the orbital planes of the exoplanets. If exoplanets orbit in a plane perpendicular to our direction of view, we would have no idea they were there.