As long as you order the doors as slab plywood, then yes, all of the fronts will be slab plywood. We do not mix solid wood slab fronts with slab plywood, as the grain patterns differ between the two material.
1. Yes
2. Yes, slab plywood always runs with a vertical grain, even on the top drawer fronts
3. No, warping is not an issue with slab plywood. Even if they were solid wood, it typically would not be a problem since the fronts are secured to the drawer box, which provides good support.