I've set up the sphere as Collision with Stickiness 10 and Friction 1.0. When falling on the sphere the confettis follow its surface but stay horizontal, which means they penetrate the surface of the sphere when they should stay tangent, and then they continue to follow the surface down to the "South Pole" instead of falling off when they reach the equator of the sphere.
For the rotation, make it Dynamic in the particle settings
For the intersection, create a second sphere and make it a collision object (this will be your hit box) and enable Size Deflect in the particle system, then scale down the second sphere until the particles hit the first sphere near its surface (because the size deflect will make the particles deflect a few centimeters from the surface). Of course delete the collision from the first sphere.
For the stickiness, for confetti you should use 0 stickiness, 0 friction (or at least low values of it) and 1 damping
I didn't find a way to do exactly what you want, but You can do it fall that way at least for one perspective.
- Physics > Size Deflect will prevent the clipping completly.
- Rotation > Dynamic will make the particles turn correctly, you just need to adjust the phase to make it look right. You will see why I did say it's only for one perspective and I don't think there is a simple way around it yet...